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FM receiver study chosen such that no third order inter-modulation products occur in the pass-band of the receiver tuned to the low level signal. If this is not possible either the power of the low power transmission should be increased or a gap-filler should be installed to achieve the required protection ratio.
Introduction The Expertengruppe UKW 2001 has recommended to optimize FM-networks because FM will remain the main modulation technique for radio for the coming fifteen to twenty years. FM networks could be optimized by revising the protection ratios used for frequency planning. The goal of this study is twofold. First, the technical characteristics of a representative group of present day FM receivers should be assessed. Second, the protection ratios for the network configurations conventional, same programme and HF-synchro should be determined using a reference receiver. Approach From a set of thirty present day FM receivers, consisting of ten car radio, ten portables and ten handhelds, the technical characteristics were determined as follows. First, the characteristics of the individual receivers were measured according to Recommendation ITU-R BS.641. Based on these measurements a good, a reference and a bad receiver was selected from the total group of receivers. Next, the protection ratios for frequency planning for three different network configurations based on subjective assessment of sound samples recorded with the good, the reference and the bad receiver were determined. Finally, the high signal performance and the RDS switching behaviour of a select group of receivers was investigated. This summary will present the results and the conclusions for each of these steps. Results and conclusions For this study the radio-frequency protection ratio curve was used to characterize a receiver. This protection curve is determined according to Recommendation ITU BS 641. Initial measurements showed however that some of the car radios and most of the portables and handhelds were not able to meet the minimal audio-frequency signal-to-interference ratio of 56 dB. With a audio-frequency signal-to-interference ratio of 46 dB it was possible to measure about eighty percent of the receivers. The rest was discarded. The results of these measurements are presented in the figure below.
KENWOOD KDC-3024A [C] P NASONIC CQ-RDP162N [C] A P NASONIC CQ-RDP003N [C] A BECKE MEXICO PRO CD 4627 [C] R BLAUPUNKT WOODSTOCK DAB 52 [C] SUP ERTECH AR-921 CD [C] JVC KD- SX997R [C] JVC KS- FX480REX [C] VDO DA YTON CD 2200 [C]
0 -400 -300 -200 -100 -300 400
SANYO DTA-300M [P] P HILIP AZ3012 [P] S SANYO DC- DA1000 [P ] SONY CFD-S550L/SC [P] THOMSON RR 600CD [P] DIGITALWAY FD100 [H] P HILIP AZT9500 [H] S SONY ICF-C1200 [H] UNITE DM2595-2 [H] D AIWA HS-RM539 [H] SONY WM-FX491[H]
KENWOOD KDC-3024A [C] PANASONIC CQ-RDP162N [C] PANASONIC CQ-RDP003N [C] BECKER MEXICO PRO CD 4627 [C] BLAUPUNKT WOODSTOCK DAB 52 [C] SUPE RTE AR-921 CD [C] CH JVC KD-SX997R [C] JVC KS-FX480REX [C] VDO DAYTON CD 2200 [C]
SANYO DTA-300M [P] PHILIP AZ3012 [P] S SANYO DC-DA1000 [P] SONY CFD-S550L/SC [P] THOM SON RR 600CD [P ] DIGITALWAY FD100 [H] PHILIP AZT9500 [H] S SONY ICF-C1200 [H] UNITE DM2595-2 [H] D AIWA HS-RM 539 [H] SONY WM-FX491[H]
Figure 2.1: Radio-frequency wanted-to-interfering signal ratio (wtisr) for twenty receivers recorded according to ITU Recommendation BS.641. The category to which the receivers belongs is indicated between brackets. The letters C, P and H are used for respectively the category car radios, portables and handhelds.
Details of the measurements can be found in Appendix A. About half of the receiver did not have an antenna input. This meant the signal from the multi-source generator had to be transmitted via the fixed or wire antenna of the receiver under test. Disadvantage of this method is that the input level at the input of the receiver is not known. This, however, is not necessary for the determination of the radio-frequency protection ratio if it is assumed that ratio between the output level of the transmitter and the input level of the receiver is the same for both the wanted signal and the unwanted signal. 2.4.2 Sensitivity Besides the radio-frequency protection ratio curve, the sensitivity of each receiver was also measured. The sensitivity is the signal level, in dBV, that is needed for an audio-frequency signal-to-interference ratio of 20dB. The 20 dB audio-frequency signal-to-interference ratio was chosen so that the sensitivity of all receiver could be measured. Not all receivers can be compared based on sensitivity since sensitivity depends on the way the signal is fed to the receiver. For this study three different feeds are used. The first one is a direct feed. This type of feed can be used for receivers that are equipped with an RF-input connector. All receivers from the category car radios have such a feed. Advantage of this type of feed is that the signal level at the input of the receiver is equal to the signal level at the output of the transmitter. The second type of feed uses a alligator clip to transmit the signal onto the fixed antenna. For the third type of feed the receive antenna, a wire, is wrapped around the transmit antenna. In both cases it is not possible to determine the exact input level. This means that only the sensitivity of receivers that use the same type of feed can be compared. Page 15
FM receiver study To get an indication of the actual input level of the receivers that use an indirect feed, two of such receivers are modified. The fixed antenna of the Sanyo DC-DA1000 and the wire antenna of the Sony WM-FX491 were replaced by a BNC connector. The table below lists the sensitivity before and after the modification. Sanyo DC-DA1000
Sensitivity before modification [dBV] Type of feed Sensitivity after modification [dBV] Type of feed 19,30 Indirect via fixed antenna 7,90 Direct via BNC connector
35,40 Indirect via wire 29,20 Direct via BNC connector
Table 2.1: Indication of actual sensitivity for receivers which are fed indirectly.
Table 2.1 indicates that the loss due to the indirect coupling is 11,40 dB in case the signal is transmitted to the fixed antenna via an alligator clip and 6,20 dB in case the transmitted by wrapping the wire antenna of the receiver around the wire antenna of the transmitter. 2.5 Selection of the reference receiver The radio-frequency wanted-to-interfering signal ratios are used to select a reference receiver. This is done in two steps. The first step is to determine and average and mean radio-frequency protection ratio curve. The second step is to select the receiver which radio-frequency protection ratio curves is closest to the mean and median radio-frequency protection ratio curve. Before the mean and median radio-frequency protection ratio can be determined, the following question needs to be answered: How many receivers from each category are used for determining the average protection ratio curve? With the adjusted minimal value for the audio-frequency signal-to-noise ratio it is possible to determine the protection ratio curves for nine car radios, five portables receivers and six walkmans. In principle the are two options for the determination of the mean and median audio-frequency protection ratio curves. In the first option the mean and median curve will be based on an equal number of receivers per category. The category with the lowest number of receivers determines the total number of receivers. Consequently, in the other two categories receivers have to be dropped. The problem then is which receiver is, and which receiver is not, taken into account. In the second option the mean and median will be based on all receivers. Although this means that the three categories are not equally represented it was decided to determine the mean and median protection ratio curve based on all receivers. This decision is (primarily) based on the fact that the difference between the portable and the walkman category is arbitrary. A division into two categories is more logical since the car radios perform significantly better than the remaining receivers. In that perspective the two categories are more or less equally represented: nine car receivers and eleven other receivers. Based on the mean and median protection ratio curve a reference receiver will be selected. This receiver is used to record the sound samples which will be used in the subjective tests. Page 16
FM receiver study The selection of the average receiver is based on the mean absolute deviation (MAD) from the mean and the median. These mean absolute deviations are calculated for channel spacings ranging from 400 kHz to 400 kHz in 50 kHz steps. The results are listed in table 2.7. Reciever
Kenwood KDC-3024A Panasonic CQ-RDP162N Panasonic CQ-RDP003N Becker Mexico Pro CD 4627 Blaupunkt Woodstock DAB 52 Supertech AR-921 CD Jvc KD-SX997R Jvc KS-FX480REX Vdo Dayton CD 2200 Sanyo DTA-300M Philips AZ3012 Sanyo DC-DA1000 Sony CFD-S550L/SC Thomson RR 600CD Digitalway FD100 Philips AZT9500 Sony ICF-C1200 United DM2595-2 Aiwa HS-RM539 Sony WM-FX491
22,3 10,8 20,3 19,4 24,6 5,9 20,4 21,4 6,4 16,4 5,8 4,6 22,9 8,6 16,4 10,7 16,1 23,4 14,3 17,7
23,8 11,9 21,7 20,8 26,2 3,5 21,8 22,8 7,5 14,8 6,1 3,6 21,3 7,0 13,4 9,3 14,7 22,0 12,8 16,0
Table 2.1: Mean average deviation (mad) from the mean and the median.
The Sanyo DC-DA1000 has the lowest mean average deviation from the mean and the second lowest mean average deviation from the median. Therefore, this receiver is selected as reference receiver. In comparison with the ITU Recommendation BS.641 this study uses a different start and stop value for the audio-frequency signal-to-noise ratio. Due to these different values it is not possible to compare the protection ratio curve of the Sanyo DC-DA1000 with the curve from ITU Recommendation BS.412-9. It is however possible to compare the Sanyo DC-DA1000 with the Zero-Base reference receiver, the NAD1600. To make this comparison possible the radio-frequency protection ratio curve of the Zero-Base reference receiver was recorded with the same start and stop values as were used for receiver listed in tables 2.1 to 2.3. Figure 2.1 depicts the protection ratio curves of the Sanyo DCDA1000 together with the protection ratio curve of the Zero-Base reference receiver, the average and median protection ratio curve from this study.
AVERAGE RECEIVER M EDIAN RECEIVER SANYO DC-DA1000 [P ] ZEROBASE REFERENCE RECEIVE R
Figure 2.1: Comparison between the Zero-Base reference receiver, the Sanyo DC-DA1000, the mean and the median receiver of this study.
2.6 Selection of the good and the bad receiver Besides the reference receiver, a good and bad receiver will be used for recording sound samples. It is preferred that the good, average and bad receiver each belong to a different category. Therefore, the good and the bad receiver will be selected from a category other than portables. Since car radios are better receivers than walkmans the good receiver will be selected from the category car radios. Consequently, the bad receiver will be selected from the category walkmans. The fact that the good receiver doesnt have to be the best receiver makes the selection of a good receiver somewhat arbitrary. The same holds for the selection of the bad receiver. Considering the shape and position of the protection ratio curves with regard to the reference radio-frequency protection ratio curve three receivers were considered as good receivers and three as bad receivers. Candidates for the title good receiver are: The Jvc KD-SX997R, the Jvc KS-FX480REX and the Blaupunkt Woodstock DAB52. Candidates for the title bad receiver are: the United DM2595-2, the Sony ICF-C1200 and the Sony WM-FX491. In mutual agreement the Blaupunkt Woodstock DAB52 car radio was selected as good receiver and the Sony WM-FX491 was selected as bad receiver. The protection ratio curves of the good and bad receiver are depicted in figure 2.4.
BLAUPUNKT WOODSTOCK DAB 52 [C] SANYO DC-DA1000 [P ] SONY WM-FX491[H]
Figure 2.1: The protection ratio curves of the good, the reference and the bad receiver.
3 Recording of the sound samples
For the subjective tests sound sample via a simulated radio link between the transmitters and receiver are recorded. The simulated radio link makes it possible to do for different conditions. For this study the frequency difference and the delay between the wanted and interfering transmitter as well as the ratio between radio-frequency level of the wanted and interfering transmitter are varied. The sound samples are recorded for three different network configurations. Per network configuration three different receivers are used: the good, the reference and the bad receiver. Details of the recordings are explained in the next paragraphs. 3.1 Test setup Figure 3.1 shows the diagrams of the measurement arrangements which are used for the recording of the sound samples. The modulating signals originate from industrial personal computers (IPCs) 1 and 2. The audio output of the receiver under test is fed to IPC 3. This IPC is used for recording the sound samples All IPCs are equipped with a professional sound card. An output balancing unit (OBU) is placed between the audio output of the receiver and the input of the IPC to go from unbalanced to balanced audio. For the network configurations conventional and same programme two analogue exciters, with integrated stereo encoders, were used. In case of the network configuration same programme the exciters are locked to an external frequency reference, in case of the conventional network configuration they are not. The network configuration HF-synchro uses two digital exciters which are also locked to an external frequency source. The RDS and stereo encoders are integrated in the digital exciter. Table 3.1 gives the details of the equipment that is used. Equipment
Musicam Encoders Elettronika MIRA 30S BE Fxi60 Azted Audemat RDS encoder Agilent Frequency counter (Frequency reference) MP2700 Multipath Fading Emulator Rhode& Signal Generator (Local Oscillator) Nozema n.v. AES/EBU Audio splitter Output Balacing Unit EA811 Nozema n.v. Analogue Audio splitter Aztec Audemat FM-MC3.2
CN, SP, SN CN, SP SN CN, SP SP, SN CN, SP, SN CN, SP, SN SN CN, SP, SN CN, SP CN, SP, SN
Musicam1,2 and 3 0202,0206 8011895-001, -
Table 3.1: Equipment used for the recording of the sound samples. The column network configuration (nc) indicates for which network operation mode the equipment was used.
RECEIVER UNDER TEST
(B) Figure 3.1: Measuring arrangement for the recording of sound samples. (A) measuring arrangement for the conventional network configuration. (B): measuring arrangement for the network configurations same programme and synchro.
The frequency of the wanted transmitter is set to 100 MHz, the frequency of the interfering transmitter is equal to the frequency of the wanted transmitter plus the frequency difference. The situation where the interfering frequency is higher than the wanted frequency corresponds to the right-hand side of the protection ratio curves. The wanted and interfering transmitter are modulated in accordance with Swiss regulation. The requirement that maximum 10% of the Page 21
FM receiver study instantaneous frequency deviations must lie in the interval from 75 to 85 kHz turned out to be leading. 3.2 Source sound samples Source sound samples are the sound samples that are used to frequency modulate the transmitters. Three different types of source sound samples are used. The first type is speech. For this type a fragment from the Dutch radio station Radio 1 is taken. The second and third type are respectively pop/rock and classical music. For Pop/rock a fragment of Need you tonight by INXS is taken. For classical music a fragment of Der Nussbaum by Vesselina Kassarova is used. All fragment are about one minute in length. 3.3 Sound sampled recorded with the reference receiver The reference receiver is used to record sound samples with speech and classical music as wanted signal. This is done for all three network configurations. The different conditions per network mode - frequency difference, delay and signal to noise ratio - that are used are listed in tables 3.2 to3.4. Network configuration: conventional f[kHz] 100 200
36; 42; 48; 54
The participants took part in both tests and always started with the pairwise comparison test. In the PWC test, ten younger and ten older participants were presented with the speech samples, and the other ten younger and ten older participants with the classical music samples. In the MOS test, all 40 participants were presented with the speech and classical music samples. The samples, stored on a PC, were played back through high-quality headsets, the sound was set at a comfortable listening level (speech at 68 dBA, classical music at 66 dBA). 4.2.1 Pairwise comparison The participants listened to the samples presented in pairs. Their task was to compare the two stimuli in each pair and to indicate what stimulus had a higher sound quality. Thus, participants gave relative judgments. With 4 PWC runs (containing 25 different conditions), each participant judged 246 pairs of samples, as explained earlier. Each pair was presented only once. During the presentation of a sample pair, the participants could hear the samples by mouse clicking on the buttons labelled fragment 1 or fragment 2 on a computer display. They could repeat the samples as often as they wanted. After hearing both samples, the participants made their judgments by mouse clicking on the buttons labelled fragment 1 is better or fragment 2 is better on the display. After they made their selection, a new pair of samples was presented. For the presentation of the 4 PWC runs, ten different orders were created, resulting in 2 participants (a younger and an older) receiving the same order of runs. The order of the sample pairs within each run was different for each participant (randomized). Prior to the first PWC run, the participants were presented with 10 practice sample pairs, to familiarize them with the experimental procedure and with the sample quality range to be expected in the experiment. In total, the PWC test (4 runs) took approximately 2 hours, including short breaks. 4.2.2 Mean Opinion Score In this test, the participants rated the quality of the individually presented samples using a five-point scale from bad (1) to excellent (5) and entered their ratings on a computer Page 24
FM receiver study display using a keyboard. The presentation of the sample was followed by a warning signal to warn the participants that they should enter their ratings (there was a 2-sec interval between samples). Each sample was presented only once. The participants were tested in groups of 3 or 4, in separate testing booths with individual headphones. For each group of participants, the order of the speech samples (MOS run 1) and of the classical music samples (MOS run 2) was different. About twenty (half) of the participants started with the speech samples and the other participants with the classical music samples. Prior to each MOS run, the participants were presented with eight practice trials to familiarize them with the experimental procedure and with the quality range for both the speech and classical music samples to be expected in the experiment. In total, the MOS test (2 runs) took approximately 25 minutes, including a short break. 4.3 Analysis and results of the pairwise comparison For each participant, the preference matrix of the samples was determined. Table 4.1 illustrates an artificial comparison between five samples. A cell value of 1 indicates that the column variable is preferred over the row variable, a cell value of 0 indicates that the row variable is preferred. The sum of the column reflects the number of times the column variable is preferred over all row variables. Sample A B C D E Column total A 3 B 0 Preference C 4
Figure 4.8: Mean opinion score as a function of the signal-to-interference ratio for speech recorded in a conventional, same programme and HF-synchro network with the Sanyo receiver.
If a quality criterion of MOS = 3.51 is regarded as acceptable, then the following protection ratios can be obtained.
The criterion of MOS = 3.5 is similar to the criterion applied in the ZeroBase study.
Figure 4.9: The protection ratio as function of the frequency distance based on a mean opion score of 3,5 for speech recorded with the Sanyo receiver.
Figure 4.10: The protection ratio as function of the frequency distance based on a mean opion score of 3,5 for classical music recorded with the Sanyo receiver.
0 --20 -30
CONV SAME SYNC_D50 SYNC_D100 f [kHz] 150 200
Figure 4.11: The protection ratio as function of the frequency distance based on a mean opion score of 3,5 for speech recorded with the Blaupunkt receiver.
f [kHz] 150 200
CONV SAME SYNC_D50 SYNC_D0
Figure 4.12: The protection ratio as function of the frequency distance based on a mean opion score of 3,5 for speech recorded with the Blaupunkt receiver.
It should be noted that the protection ratios are obtained by means of interpolation and extrapolation and may differ from the values obtained through real experimental measurement. The protection ratios show some surprising results. First, the network configuration same programme resulted in a lower protection ratio than HF-synchro. The opposite was expected. Second, a higher delay didnt always result in a higher protection ratio for the network configuration HF-synchro. Third, the Sony required a higher protection ratio for f=200 kHz than for f=0 kHz. This result is in contradiction with the results of the objective measurements. Fourth, the bad receiver required a lower protection ratio for f=0 kHz for both the network configuration HF-synchro and same programme than the good receiver. The consequences of these protection ratios for frequency planning will be discussed in the next chapter.
FM receiver study 5.5 Planning considerations
5.5.1 Usable field strength calculations For calculating usable field strength, the nuisance fields of relevant interfering transmitters should be calculated. Transmitters carrying the same programme should be identified. This may require a special code in the transmitter database. The nuisance field of these transmitters should be calculated with the reduced protection ratios (see section 7.3). The nuisance field of the other relevant transmitters should be calculated with the protection ratios for conventional networks (see section 7.2). All relevant nuisance fields should be combined using the agreed method (e.g power sum). 5.5.2 Optimised networks The use of protection ratios for same programme networks may lead to higher frequency efficiency in case coverage areas are interference limited. However flexibility in network operation is reduced. If a transmitter that is part of the network for which the reduced protection ratios are applied, needs to carry another programme, either a regional opt-out or a completely different programme, a new network planning is required; the reduced protection ratios are not applicable any more. The application of transmitters with frequencies N 200 or 300 kHz with the same programme is particularly useful for coverage optimisation in the periphery of a coverage area of a transmitter with frequency N. As there is a negative protection ratio, either the transmitter with frequency N or the one with N 200 or 300 kHz (having the same programme) can always be received. Another application could be made in case of a more or less full replanning. A network carrying the same programme could consist of several transmitters having frequency differences of 0 or 100 kHz. The interference zones between these transmitters should be covered by transmitters on other frequencies. It may also be possible by careful planning to situate the interference zones in areas of low population densities. Also in this case coverage areas can be optimised by transmitters with frequency differences of 200 or 300 kHz as described above. An example of a network that has been planned on the basis of reduced protection ratios for transmitters carrying the same programme is shown in annex [7.1]. This network shows the combination of cases indicated above. The network consists mainly of two sets of frequencies, around 103.1 MHz and around 97.7 MHz respectively. Although the example shows the way planning could be done, it should be noted that the protection ratios in this example are different than those advised in this report. Furthermore also other criteria and methods in the example are different than those recommended by ITU. 5.5.3 International frequency coordination Reduced protection ratios for networks carrying the same programme are not contained in GE84 plan and are not recommended by ITU. Also the GE84 transmitter databases do not contain provisions for indicating that transmitters are working in networks carrying the same programme. Calculations done in the framework of GE84 frequency co-ordinations can therefore not take into account the reduced protection ratios. The usable field strength at test points in the coverage area of transmitters with the same programme, in these circumstances may therefore be much higher than calculated for national frequency planning purposes. Page 36
FM receiver study 3 - Measuring the radio-frequency protection ratio curve. The following procedure is repeated for frequency differences ranging from 500 kHz to 5 MHz in steps of 500 kHz: The output levels of the unwanted transmitters are kept equal and are simultaneously adjusted to obtain an audio-frequency signal-to-interference ratio of 40 dB at the audio-frequency output of the receiver. In this case, the weighting network of the modulation analyzer must be switched in (i.e. CCIR WEIGHTED) and the QUASI-PEAK detector must be selected. The ratio between the radio-frequency levels of the wanted and unwanted transmitters is the required radio-frequency wanted-to-interfering signal ratio. 7.2 Results The high signal performance tests are executed for two receivers from the category portables a handhelds. For the first category the Sanyo DC-DA1000 and the Sony CFD-S550L are tested, for the second category the Philips AZT9500 and the Sony WM-FX491.
0 -1 --10 -15 -20 -25 -30 -35 f [MHz]
30dBpW 50dBpW 70dBpW
Figure 7.1: Radio-frequency wanted-to-interfering signal ratio as a function of frequency difference for the Sanyo receiver.
wtisr [dB] -5 -4 -3 -2 -1 --10 -15 -20 f [MHz] 5 30dBpW 50dBpW 70dBpW
Figure 7.2: Radio-frequency wanted-to-interfering signal ratio as a function of frequency difference for the Sony receiver.
Figure 7.3: Radio-frequency wanted-to-interfering signal ratio as a function of frequency difference for the Philips receiver.
wtisr [dB] -5 -4 -3 -2 -1 -5 50dBpW 70dBpW
-10 f [MHz]
Figure 7.4: Radio-frequency wanted-to-interfering signal ratio as a function of frequency difference for the Philips receiver.
The results clearly indicate that inter-modulation products significantly deteriorate the performance of the receiver under test. The frequencies of the second and third order intermodulation product, expressed in in fw and f, can found in table below. Order of the IM products Second Third Frequencies of the IM-products f, 2f, 2fw, 2f w+f, 2fw+2f, 2f w+3f ,2fw+4f fw-2f, f w-f, fw, f w+f, f w+2f, fw+3f, f w+4f, 3fw, 3f w+f, 3fw+2f, 3fw+3f, 3f w+4f, 3fw+5f, 3f w+6f
Table 7.1: Frequencies of the first, second and third order inter-modulation products for the choice of frequencies in accordance with (1).
Table 8.1: Frequency combinations for RDS switching behavior due to differences in radio frequency levels.
The carrier frequency of sources A and B are set according to table 8.1. The radio frequency levels of both sources are set to the same level. The receiver under test is tuned to source A. Next the radio frequency level of source A is lowered, in steps of 1 dBV, until the receiver under test switches to source B. The radio frequency level of source A at the time of the switch over is the required radio frequency switching level. 8.1.2 RDS switching behavior due to multipath
This test represents the situation where the receiver receives a number of reflected signals. Normally a channel simulator is used for multi path testing. Due to the fact that such a device was not available an alternative approach for measuring multi path effects is explained below. This alternative test can be split up into the following two step: 1 - Setting up the transmitters. Page 44
FM receiver study Sources A and B of the multi source generator are frequency modulated with a 500 Hz sinusoidal tone and RDS. For both sources the frequency deviation due to RDS is set to 2 kHz. Station C of the multi source generator is frequency modulated with pop music. The outputs of sources A, B and C are combined and fed to the receiver under test. 2 - Measuring the radio frequency switching level The following procedure is repeated for the following combinations of carrier frequencies: Combination Source A, f (MHz) Source B, f (MHz) 1 90,0 105,90,0 90,105,0 90,90,0 89,7
Table 8.1: Frequency combinations for RDS switching behavior due to multipath.
The carrier frequency of sources A and B are set according to Table 8.1. The carrier frequency of source C is made equal to that of source A. The radio frequency levels of sources A and B are set to the same level. The receiver under test is tuned to source A. The radio frequency level of source C is chosen such that it does not lead to any interference on channel A. Next the radio frequency level of source C is raised, in steps of 1 dBV, until the receiver under test switches to source B. The radio frequency level of source C at the time of the switch over is the required radio frequency switching level. 8.2 Results
8.2.1 RDS switching behavior due to differences in radio frequency levels The level of sources A and B is set to 60 dBV. The radio-frequency level of source A at the time of switch over is given in table 8.3. Receiver
Blaupunkt Woodstock DAB52 Jvc KD-SX997R Vdo Dayton CD2200 Sony CDX-M850MP Becker Mexico Pro CD4627
f, source A (MHz) & f, source B (MHz)
90,0&105,0 90,0&90,1 105,0&90,0 90,0&89,9
Jvc KS-FX480REX Panasonic CQ-RDP003N Panasonic CQ-RDP162N
Table 8.1: Results for RDS switching behaviour due to differences in radio-frequency levels. The value in the cell is the radio-frequency level, in dBV, of source A when the receiver switches from source A to source B.
Based on the results he following conclusions can be drawn: Page 45
FM receiver study When the frequency difference is small, a small reduction of the radio-frequency level makes all receivers switch over. When the frequency difference is large (f>300 kHz), some receivers accept a low radio-frequency level before switching over while other receivers already switch over after a small reduction of the radio-frequency level. The Blaupunkt Woodstock DAB52 and the JVC KD-SX997 show an asymmetric switching behaviour for large frequency differences. The reason for this behaviour is not clear. The Sony and the Becker switch over after a small reduction in radio-frequency level for both small and large frequency differences. For the other car radios the switching behaviour depends on the frequency differences.
8.2.2 RDS switching behavior due to multipath The level of sources A and B is set to 60 dBV. The radio-frequency level of source C at the time of switch over is given in table 8.4. Receiver
90,0&105,0 90,0&90,3 105,0&90,0 90,0&89,7
Table 8.1: Results for RDS switching behaviour due to multipath. The value in the cell is the radio-frequency level, in dBV, of source C when the receiver switches from source A to source B.
In general all receivers, except the Jvc KS-FX480REX, show a comparable multipath behaviour.
Appendix A: Detailed results of the protection ratio measurements
Tof Rf-w2isr max Wt-rfl: rfw2isr max M/s Ut-afl: dev=32 kHz Wt-afl: afs2ir=46 dB Ut-dev Wt-dev Wt-rfl: SNR=20dB Wt-rfl: SNR=20dB corrected Wt-rfl: afs2ir=46 dB Rf-w2isr: df= 400 kHz Type of feed. The following tof were used:1-Direct feed (D), 2-Indirect feed using an alligator clip (I-AC) and 3-Indirect feed using a wire antenna (I-W). The maximum radio-frequency wanted-to- interfering signal ratio. The radio-frequency level of the wanted transmitter to obtain the maximum radio- frequency wanted-to-interfering signal ratio. Mono/stereo. The audio frequency level of the unwanted transmitter to obtain a frequency deviation of 32 kHz. The audio frequency level of the wanted transmitter to obtain a audio- frequency signal-to- interference ratio of 46 dB. The frequency deviation of the unwanted transmitter. The frequency deviation of the wanted transmitter. The radio frequency level of the wanted transmitter to obtain a signal-to-noise ratio of 20 dB. The corrected, due to using an indirect feed, radio frequency level of the wanted transmitter to obtain a signal-to-noise ratio of 20 dB. The radio frequency level of the wanted transmitter to obtain a audio- frequency signal- to-interference ratio of 46 dB. The radio-frequency wanted-to- interfering signal ratio for a frequency difference between the wanted and unwanted transmitter of 400 kHz.
Table A.1: Detailed results of the radio-frequency protection ratio measurements.
Appendix B: Example of a same programme network
Table B.1: Example of a same programme network in The Netherlands
Appendix C: Reception problems due to inter-modulation
An FM site in Rotterdam transmits the frequencies indicated in the table 1 below. Station Radio TV West Business News Radio RTV Rijnmond Noordzee FM Sky Radio Radio 538 Veronica RTL FM
Table C.1: FM transmissions fromRotterdam
f (MHz) 89.3 91.3 93.4 100.4 101.5 102.7 103.2 104.6
The ERP on 102.7 MHz is highest (100 kW) and within about 6.5 km from the transmitter the field strength is 95 dBV/m or more. FM networks Radio 1, 2 and 3 are not transmitted from the site in Rotterdam, but from Lopik about 45 km away. The field strength of the Lopik transmissions near the site in Rotterdam is about 61 dBV/m. Reception of Radio 1, 2 and 3 is interfered by third order inter-modulation products within 6.5 km from the Rotterdam site as indicated in table 2. Station Radio 1 Radio 2 Radio 3 Frequency (MHz) 98.9 92.6 96.8 Frequency of 3rd order inter-modulation-products (MHz) 98.6 98.7 99.0 99.1 99.2 92.3 92.4 92.5 92.7 92.9 96.5 97.0 97.1
Table C.2: Frequency of the third order inter-modulation products near Rotterdam.
Frequencies could not be changed and the solution was to install at the Rotterdam site three fill-in transmitters to improve coverage of Radio 1, 2 and 3. It was not possible to find intermodulation free frequencies for the fill-in transmitters. Consequently the ERP of the fill-in transmissions should be high enough to respect the required protection ratios in case of high signal performance.
Appendix D: Photographs of tested receivers
BECKER MEXICO PRO CD 4627
BLAUPUNKT WOODSTOCK DAB 52
SUPERTECH AR-921 CD
Car radios continued
Table D. 1: Photographs of the tested car radios.
VDO DAYTON CD 2200
GRUNDIG LUNA RP 9200 PPL
GRUNDIG OCEAN BOY 350
Table D. 2: Photographs of the tested portables.
THOMSON RR 600CD
GRUNDIG CITY BOY 52
KUSC-FM Technical Info: Station Status Licensed Class B Non-Commercial FM Station Area of Coverage View Coverage Map Effective Radiated Power 39,000 Watts Height above Avg. Terrain 891 meters (2925 feet) Height above Ground Level 30 meters (98 feet) Height above Sea Level 1689 meters (5545 feet) Antenna Pattern Directional Transmitter Location 34 12' 48" N, 118 03' 41" W License Granted April License Expires December Last FCC Update November 29 2005
KUSC-1-FM Technical Info: Station Status Licensed Class D FM Booster Station Parent Station KUSC-FM Area of Coverage View Coverage Map Effective Radiated Power 175 Watts Height above Ground Level 5 meters (16 feet) Height above Sea Level 1056 meters (3467 feet) Antenna Pattern Directional Transmitter Location 34 19' 30" N, 118 34' 36" W License Granted October License Expires December Last FCC Update November This station may also be operating under the following Construction Permit: Status Construction Permit for a Class D FM Booster Station Area of Coverage View Coverage Map Effective Radiated Power 200 Watts Height above Ground Level 6 meters (20 feet) Height above Sea Level 1140 meters (3743 feet) Antenna Pattern Directional Transmitter Location 34 19' 47" N, 118 35' 57" W Construction Permit Granted May Construction Permit Expires May Last FCC Update May 18 2006
Das Strahlungsdiagramm des Hauptsenders in Los Angeles (Bild oben) sowie des Umsetzers in Santa Clarita (Bild unten)
Threads im Radioforum zum Thema UKW-Gleichwellennetze Im Radioforum wurden mehrere interessante und lngere Threads zum Thema UKW-Gleichwellennetze erffnet. Hier eine kurze bersicht mit URL-Angaben: http://forum.mysnip.de/read.php?8773,6423 Titel: UKW-Gleichwellen Begonnen am 20.10.2002 http://forum.mysnip.de/read.php?8773,159672 Titel: UKW-Sender fr Gleichwelle synchronisieren wie wird's gemacht? Begonnen am 6.1.2005 http://forum.mysnip.de/read.php?8773,163678 Titel: Warum keine Gleichwelle auf UKW? Begonnen am 30.1.2005 http://forum.mysnip.de/read.php?8773,466073 Titel: Die Gleichwellen des Bayrischen Rundfunk wie laufen die in der Praxis? Begonnen am 22.12.2006 http://forum.mysnip.de/read.php?8773,470458 Titel: Gleichwellenfunk auf UKW? Begonnen am 12.1.2007
= 300; = +10 ( > 45 N = 320; = -05 ( 0 to 45 N) = 300; = -25 ( < 0)
Fresh investigations of the near-ecliptic Aquarid and Capricornid (CAP) streams using IMO and other visual and video data have been published in recent years. These have generally confirmed the known details for the stronger Southern -Aquarid (SDA) and CAP maxima, but the SIA and NIA did not appear at all clearly, unsurprising given their borderline-visible ZHRs. The greatest oddity was the NDA, for which no distinct maximum could be traced, and whose ZHRs were never better than ~ 3. A recent investigation of the ecliptical radiants showed that what was regarded as the NDA radiant is in fact entirely within the radiant area of the Antihelion Source (radiant motion on page 13). The showers SIA, NIA, and NDA are no longer included in the new Working List for 2007. Excepting the moonlit CAP, the Antihelion Source and SDA are rich in faint meteors, making them well-suited to telescopic work, although enough brighter members exist to make visual and imaging observations worth the effort too, primarily from more southerly sites. Radio work can be used to pick up the SDA especially, as the most active source, and indeed the shower can sometimes give a surprisingly strong radio signature. Such a concentration of radiants in a small area of sky makes for problems in accurate shower association. Visual watchers in particular should plot all potential shower members, rather than trying to make shower associations in the field. All SDA, CAP and ANT radiants are above the horizon for much of the night, with the fewest moonlight problems in the period of about August 8 - 24. Perseids (PER) Active: Maximum: ZHR = Radiant: Radiant drift: v = TFC: July 17 August 24 August 13; 5h 7h30m UT ( = 1400 1401) - but see text 100 = 046; = +58 see Table km/s; r = 2.6 = 019; = +38 and = 348; = +74 before 2h local time = 043; = +38 and = 073; = +66 after 2h local time ( > 20 N) = 300; = +40; = 000; = +20 or = 240; = +70 ( > 20 N)
-Capricornids (CAP) Active: Jul 3 August 15 Maximum: July 30 ( = 127) ZHR = 4 Radiant: = 307; = -10 Radiant see Table 6 drift: v = 23 km/s r= 2.5 TFC: = 255 to 000; = 00 to +15 choose pairs separated by about 30 in ( < 40 N)
The Perseids were one of the most exciting and dynamic meteor showers during the 1990s, with outbursts at a new primary maximum producing EZHRs of 400+ in 1991 and 1992. Rates from this peak decreased to ~ 100 - 120 by the late 1990s, and in 2000, it first failed to appear. This was not unexpected, as the outbursts and the primary maximum
IFC: = 330; = +60 and = 300; = +30 ( > 20 N)
(which was not noticed before 1988), were associated with the perihelion passage of the Perseids' parent comet 109P/Swift-Tuttle in 1992. The comet's orbital period is about 130 years, so it is now receding back into the outer Solar System, and theory predicts that such outburst rates should dwindle as the comet to Earth distance increases. However, some predictions suggested 2004 - 2006 might bring a return of enhanced rates ahead of the usual maximum, and in 2004 a short, strong peak happened close to that anticipated pre-peak time. After that, activity seemed to be roughly normal in 2005, and the moonlit 2006 return was still to come when this text was prepared, but nothing untoward was predicted for 2007 in any case. An average annual shift of +005 in the of the old primary peak had been deduced from data, and allowing for this could give a possible recurrence time around 9h UT on August 13 ( = 14016), if so a little after the most probable maximum, that of the traditional peak always previously found, which is given above. Another feature, seen only in IMO data from 1997 - 99, was a tertiary peak at = 1404, the repeat time for which would be 15h UT on August 13. Observers should be aware that these predictions may not be an absolute guide to the best from the Perseids, and plan their efforts accordingly, so as not to miss out, just in case! Whatever happens, and whenever the peak or peaks fall around August 13, new Moon on August 12 creates perfect observing circumstances this year. For midnorthern latitudes, the radiant is sensibly observable from 22h - 23h local time onwards, gaining altitude throughout the night. The UT morning-hour maxima suggested here would be best-viewed from across North America and northern South America, while the possible ~ 15h UT peak would fall best for Far Eastern Asia. Visual and still-imaging observers should need little encouragement to cover this stream, but telescopic and video watching near the main peak would be valuable in confirming or clarifying the possibly multiple nature of the Perseid radiant, something not detectable visually. Recent video results have shown a very simple, single radiant structure certainly. Radio data would naturally enable early confirmation, or detection, of perhaps otherwise unobserved maxima, assuming more than one takes place, if the timings or weather conditions prove unsuitable for land-based sites. The only negative aspect to the shower is the impossibility of covering it from the bulk of the southern hemisphere. -Cygnids (KCG) Active: Maximum: ZHR = Radiant: Radiant drift: v = r= August August 18 ( = 145) 3 = 286; = +59 see Table km/s 3.0
The early-setting waxing crescent Moon poses no problems for covering the expected -Cygnid peak this year by northern hemisphere observers (the locations from which the shower is chiefly accessible). Its rvalue suggests telescopic and video observers may benefit from its presence, but visual and still-imaging workers should note that occasional slow fireballs from this source have been reported too. Its almost stationary radiant results from its close proximity to the ecliptic north pole in Draco. There has been some suggestion of a variation in its activity at times, perhaps coupled with a periodicity in fireball sightings, but more data are needed on a shower that is often ignored in favour of the major Perseids during August. September Perseids (SPE) Active: Maximum: ZHR = Radiant: Radiant drift: v = r= TFC: September 5 September 17 September 9 ( = 1667) 5 = 060; = +47 see Table km/s 2.9 = 052; = +60; = 043; = +39 and = 023; = +41 ( > 10 S)
This essentially northern hemisphere shower appears to be part of a series of poorly observed sources with radiants in Aries, Perseus, Cassiopeia and Auriga, active from late August into October. British and Italian observers independently reported a possible new radiant in Aries during late August 1997 for example. Both this shower and the similarly located - Aurigids have recently been investigated by analysts Audrius Dubietis and Rainer Arlt, using IMO-standard data since 1986, and their parameters updated accordingly. Of the two known Aurigid sources, the -Aurigids (AUR) are the more active, with short unexpected bursts having given EZHRs of ~ 30 - 40 in 1935, 1986 and 1994, although they have not been monitored regularly until very recently, so other outbursts may have been missed. Only three watchers in total covered the 1986 and 1994 outbursts, for instance! The September Perseids and -Aurigids, whose activities and radiants effectively overlap one another, were combined into one source in the Working List up to 2006. Since the activity curves show evidence for two individual showers, we have split them into the September Perseids and -Aurigids in the Working List for 2007. Near September 17, activities of both showers are actually interfering, but it is not recommended to distinguish the showers as their individual radiants are not resolvable. The -Aurigid phase seems to give a weak maximum around = 181 (2007 September 24;
Radiant: Radiant drift: v = r= TFC: = 262; = +54 negligible 20 km/s 2.6 = 290; = +65 and = 288; = +39 ( > 30 N)
ZHR ~ 3, r = 2.5), but its peak time is poorly defined and may occur as late as = 191 (2007 October 4). Radiants in and near Auriga reach useful elevations after 23h - 0h local time for early autumn northern watchers. Consequently, the September Perseid peak on September 9 is favoured over the main -Aurigid one, as the Moon is almost new for it. Telescopic data to check for other radiants in this region of sky (and possibly observe the telescopic -Cassiopeids simultaneously) would be especially valuable, but imaging records and visual plotting would be welcomed, as always. Antihelion Source (ANT) in September Active: Maximum: ZHR = Radiant drift: v = r until September 25 when NTA/STA take over none 3 see Table km/s ~3
Audrius Dubietis carried out an examination of IMO data on the Piscids (now comprised by the definition of the Antihelion Source) between in early 2001, which essentially confirmed the current details on it are correct, including that this is another poorly observed part of the ecliptic-complex activity! Its radiant during the September spell is very close to the March equinox point in the sky, and consequently, it can be observed equally well from either hemisphere throughout the night near the September equinox. This year, September's waxing gibbous Moon allows about half the night for observing, with moonset between the late evening (for mid-northern latitudes) to early morning hours (for mid-southern ones). Telescopic and video techniques can be employed to study the Antihelion Source, along with methodical visual plotting. October to December A very promising final quarter to the year beckons, with only the northern- sky Ursids in December really too close to full Moon to allow useful watching. The Ursid parent comet, 8P/Tuttle, reaches perihelion next in January 2008, though past returns have not shown any directly-linked shower activity, and no predictions of enhanced rates had been made for 2007 when this text was prepared. The normal Ursid peak is due between 1h - 3h30m UT on December 22. The Leo Minorids are a shower recently added to the Working List with a maximum on October 24/25 when the Moon sets after 5h local time in the northern hemisphere. Draconids (GIA) Active: Maximum: ZHR = October October 9; 4h30m UT ( = 1954 - but see below) periodic - up to storm levels
The Draconids are primarily a periodic shower which produced spectacular, brief, meteor storms twice last century, in 1933 and 1946, and lower rates in several other years (ZHRs ~ 20 - 500+). Most detected showers were in years when the stream's parent comet, 21P/Giacobini-Zinner, returned to perihelion, as it did last in 2005 July. In 2005 October, a largely unexpected outburst happened near the comet's nodal crossing time, around = 19540 - 19544, probably due to material shed in 1946. Visual ZHRs were ~ 35, though radar detections suggested a much higher estimated rate, closer to ~ 150. The peak was found in radio results too, but it did not record especially strongly that way either. Outlying maximum times from the recent past have spanned from = 195075 (in 1998; EZHRs ~ 700), equivalent to 2007 October 8, 20h30m UT, through the nodal passage time above, to (a minor outburst in 1999, not a perihelion-return year; ZHRs ~ 10 20), equating to 2007 October 9, 10h 13h UT. The radiant is circumpolar from many northern hemisphere locations, but is higher in the pre-midnight and near-dawn hours of early October. New Moon on October 11 makes for an almost perfect observing opportunity, whatever the shower may yield even if that is nothing detectable. Draconid meteors are exceptionally slow-moving, a characteristic which helps separate genuine shower meteors from sporadics accidentally lining up with the radiant. -Geminids (EGE) Active: Maximum: ZHR = Radiant: Radiant drift: v = r= TFC: October October 18 ( = 205) 2 = 102; = +27 see Table km/s 3.0 = 090; = +20 and = 125; = +20 ( > 20 S)
A weak minor shower with characteristics and activity nearly coincident with the Orionids, so great care must be taken to separate the two sources by instrumental techniques especially video or telescopic work or visual plotting. The waxing Moon will set well before midnight (north of the equator) to about midnight (south of it), giving a fine chance to obtain more data on this shower from either hemisphere. Northern observers have a radiant elevation advantage, permitting useful access from about midnight onwards.
Orionids (ORI) Active: Maximum: ZHR = Radiant: Radiant drift: v = r= TFC: October 2 November 7 October 21 ( = 208) 25 = 95; = +16 see Table 6
Northern Taurids (NTA) Active: Maximum: ZHR = Radiant: Radiant drift: v = r= TFC: September 25 November 25 November 12 ( = 230) 5 = 058; = +22 see Table km/s 2.3 as Southern Taurids
66 km/s 2.5 = 100; =+39 and = 75; = +24 ( > 40 N) or = 80; = +01 and = 117; = +01 ( < 40 N)
The Orionid radiant, a little north of the celestial equator, is at a useful elevation by around local midnight in either hemisphere, somewhat before in the north, so most of the world can enjoy the shower. The waxing gibbous Moon will set by around 0h30m 2h30m for all observers this year, so leaving darker skies for much of the radiant's best-visible time. Audrius Dubietis' recent analysis of IMO data from showed some minor changes to past expectations, with the peak ZHR and r values varying somewhat from year to year. Maximum mean ZHRs ranged from ~ during the examined interval, with partial confirmation of a suspected 12-year periodicity in higher returns found earlier in the 20th century. This may mean stronger returns in 2008 10, and perhaps best ZHRs of around 25 this year. The Orionids were always noted for having several lesser maxima other than the main one above, helping activity sometimes to remain roughly constant for several consecutive nights centred on this peak. In 1993 and 1998, a submaximum about as strong as the normal peak was detected on October from Europe, for instance. All observers should be aware of these possibilities, as observing circumstances are particularly favourable for covering the Orionids on both October 17 and 18 under dark skies in 2007. Several visual subradiants were reported in the past, but recent video work suggests the radiant is far less complex; more imaging and telescopic work to confirm this would be useful, as visual observers have clearly had problems with the shower's radiant determination before. Taurids Southern Taurids (STA) Active: Maximum: ZHR = Radiant: Radiant drift: v = r= TFC: September 25 November 25 November 5 ( = 223) 5 = 052; = +13 see Table km/s 2.3 Choose fields on the ecliptic and ~ 10 E or W of the radiants ( > 40 S)
These two streams form part of the complex associated with Comet 2P/Encke. Defining their radiants is best achieved by careful visual or telescopic plotting, or imaging recordings, since they are large and diffuse. They have recently been studied using IMO data by Mihaela Triglav. The Taurid radiants coincide very closely with the diffuse Antihelion Source; it is actually not possible to distinguish them. The Antihelion Source although active all year round should not be reported during the activity period of the Taurids. The brightness and relative slowness of many Taurid meteors makes them ideal targets for still-imaging, while these factors coupled with low, steady, combined Taurid rates makes them excellent targets for newcomers to practice their plotting techniques on. The activity of both showers produces an apparently plateau-like maximum for about ten days in early November, and they have a reputation for producing some excellently bright fireballs at times, although seemingly not in every year. Studies by David Asher have indicated that increased Taurid fireball rates may result from a swarm of larger particles within the Taurid stream complex, and he suggested such swarm returns might happen in 1995, 1998 and 2005 most recently. In 1995, an impressive crop of bright Taurids occurred between late October to mid November, while in 1998, Taurid ZHRs reached levels comparable to the usual maximum rates in late October, together with an increased flux of brighter Taurids generally. The 2005 event was the most impressive and bestobserved yet, with a lot of, occasionally very brilliant, fireballs, and enhanced combined ZHRs of ~ 10 15, that persisted from about October 29 to November 10. Late October into early November has a full to last quarter Moon in 2007, but this will clear away nicely to allow dark skies for the usual maximum spell in November. Luckily, the next potential October-November swarm return is not anticipated till 2008, though coverage to ensure unexpected events are not happening in other years remains valuable. The nearecliptic radiants for both shower branches mean all meteoricists can observe these showers. Northern hemisphere observers are somewhat better-placed, as here suitable radiant zenith distances persist for much of the late autumnal nights. Even in the southern hemisphere, a good hours' watching around local midnight is possible with Taurus well above the horizon, however.
Leonids (LEO) Active: Maximum: ZHR = Radiant: Radiant drift: v = r= TFC:
r= TFC: 2.4 = 115; = +23 and = 129; = +20 ( > 20 N) or = 110; = -27 and = 098; = +06 ( < 20 N)
November November 18; 2h50m UT ( = 23527) but see below 15+? = 153; = +22 see Table km/s 2.5 = 140; = +35 and = 129; = +06 ( > 35 N) or = 156; = -03 and = 129; = +06 ( < 35 N) = 120; = +40 before 0h local time ( > 40 N) = 120; = +20 before 4h local time and = 160; = 00 after 4h local time ( > 00 N) = 120; = +10 before 0h local time and = 160 = -10 ( < 00 N)
Another late-year shower capable of producing surprises, the -Monocerotids gave their most recent brief outburst in 1995 (the top EZHR, ~ 420, lasted just 5 minutes; the entire outburst 30 minutes). Many across Europe witnessed it, and we were able to completely update the known shower parameters as a result. However, the proposed ten-year periodicity in such returns passed unconfirmed when nothing unusual took place during the moonlit shower of 2005. Due to this, all observers need to monitor this source closely in every year, to try to spot the next outburst. The brevity of all past outbursts means breaks under clear skies should be kept to an absolute minimum near the predicted peak. Despite the waxing gibbous Moon being only two days from full on November 22, because the radiant is well on view from either hemisphere only after about 23h local time, there will be a short dark-sky observing window between moonset and dawn twilight for northern observers then particularly. If correct, the peak timing would fall well for sites in Europe, North Africa and the Near East. Antihelion Source (ANT) in December Active: ZHR = Radiant drift: v = r taking over November see Table km/s ~3 from NTA/STA on
As the events in demonstrated, when enhanced ZHRs of ~ were found, the ending of the strong to storm Leonid returns between 1998 2002, associated with the 1998 perihelion passage of parent comet 55P/Tempel-Tuttle, have not meant an end to interest in this fascinating shower. The possibly enhanced 2006 return was still to come when this text was prepared, but there were no other predictions for potentially increased rates in force after then until 2009. Consequently, it is possible that only the usual nodal crossing peak may happen in 2007. If so, it may see a fall back to the more typical peak ZHR levels seen away from the near-perihelion returns. Nothing is certain about this year's shower however, so please be alert, and look out for any updates or fresh predictions! The Leonid radiant rises usefully only around local midnight (or indeed afterwards south of the equator), roughly the same time that the waxing gibbous Moon will be setting on November 18, so darker skies will be available for covering whatever happens. The maximum timing above would favour sites in Europe, Africa and the Near East. All observing techniques can be used. -Monocerotids (AMO) Active: Maximum: ZHR = Radiant: Radiant drift: v = November November 22; 3h10m UT ( = 23932) variable - usually ~ 5; but may produce outbursts to ~ 400+ = 117; = +01 see Table km/s
A weak part of the ecliptical meteor activity. Some brighter meteors have been photographed from it too. The shower has at least a double radiant, but the southern branch has been rarely detected. The radiant used here is a combined one, suitable for visual work, although telescopic or video observations should be better able to determine the exact radiant structure. It is well on display in both hemispheres throughout the night, but pre-midnight observing is recommended this year, as the last-quarter Moon will rise at around local midnight across the globe. Phoenicids (PHO) Active: Maximum: ZHR = Radiant: Radiant drift: November 28 December 9 December 6; 21h00m UT ( = 25425) variable - usually 3 or less; may reach 100 = 18; = -53 see Table 6
v = r= TFC:
18 km/s 2.8 = 40; = -39 and = 065; = -62 ( < 10 N)
Only one impressive Phoenicid return has so far been reported, that of its discovery in 1956, when the EZHR was probably ~ 100, possibly with several peaks spread over a few hours. Three other potential bursts of lower activity have been reported, but never by more than one observer, under uncertain circumstances. Reliable IMO data shows recent activity to have been virtually nonexistent. This may be a periodic shower however, and more observations of it are needed by all methods. Lunar circumstances for southern hemisphere watchers are pretty well perfect in 2007, thanks to new Moon on December 9. The Phoenicid radiant culminates at dusk, remaining well on view for most of the night. Puppid-Velids (PUP) Active: Maximum: ZHR Radiant: Radiant drift: v = TFC: December December ~ 7 ( ~ 255) ~ 10 = 123; = -45 see Table km/s; r = 2.9 = 090 to 150; = -20 to -60 choose pairs of fields separated by about 30 in moving eastwards as the shower progresses ( < 10 N)
42 km/s 3.0 = 088; = +20 and = 135; = +48 ( > 40 N) or = 120; = -03 and = 084; = +10 ( < 40 N)
Only low rates are likely from this minor source, making accurate visual plotting, telescopic or video work essential, particularly because the meteors are normally faint. The shower's details, even including its radiant position, are rather uncertain. Recent IMO data showed only weak signs of a maximum as indicated above. Telescopic results have suggested a later maximum, around December 16 ( ~ 264) from a radiant at = 117, = +20. This is an ideal year for making observations, with the December 9 peak falling precisely at new Moon. The radiant area is on-show virtually all night, culminating about 1h30m local time. -Hydrids (HYD) Active: Maximum: ZHR = Radiant: Radiant drift: v = r= TFC: December December 12 ( = 260) 2 = 127; = +02 see Table km/s 3.0 = 095; = 00 and = 160; = 00 (all sites - after midnight only)
This is a very complex system of poorly studied showers, visible chiefly to those south of the equator. Up to ten sub-streams have been identified, with radiants so tightly clustered, visual observing cannot readily separate them. Imaging or telescopic work would thus be sensible, or very careful visual plotting. The activity is so badly known, we can only be reasonably sure that the highest rates occur in early to mid December, coincident with the dark of the Moon this year. Some of these showers may be visible from late October to late January, however. Most PuppidVelid meteors are quite faint, but occasional bright fireballs, notably around the suggested maximum here, have been reported previously. The radiant area is onview all night, but is highest towards dawn. Monocerotids (MON) Active: Maximum: ZHR = Radiant: Radiant drift: November 27 December 17 December 9 ( = 257) 3 = 100; = +08 see Table 6
Although first detected in the 1960s by photography, \sigma-Hydrids are typically swift and faint, and rates are generally very low, close to the visual detection threshold. Since their radiant, a little over 10 east of the star Procyon ( Canis Minoris), is near the equator, all observers can cover this shower. The radiant rises in the late evening hours, but is best viewed after local midnight, so this is a perfect year for them, with an early-setting waxing crescent Moon. Recent data indicates the maximum may happen up to six days earlier than this theoretical timing, which would be almost as favourable for Moon-free watching. The shower would benefit from visual plotting, telescopic or video work to pin it down more accurately. Geminids (GEM) Active: Maximum: ZHR = Radiant: Radiant drift: v = r= December December 14; 16h45m UT ( = 2622) 2.3h 120 = 112; = +33 see Table 35 km/s 2.6
= 087; = +20 and = 135; = +49 before 23h local time = 087; = +20 and = 129; = +20 after 23h local time ( > 40 N) = 120; = -03 and = 084; = +10 ( < 40 N) = 150; = +20 and = 060; = +40 ( > 20 N) = 135; = -05 and = 080; = 00 ( < 20 N)
A weak minor shower that is usually observed only during the Geminid and Quadrantid epochs, but which needs more coverage at other times too, especially to better-define its maximum. The shower is almost unobservable from the southern hemisphere, so northern watchers must brave the winter cold to improve our knowledge of it. The radiant is at a useful elevation from local midnight onwards, and despite the peak's proximity to full Moon, several hours of dark- sky watching will still remain possible at mid-northern latitudes after moonset. Abbreviations and Tables
One of the finest, and probably the most reliable, of the major annual showers presently observable. This year, the waxing crescent Moon will set by midevening across the globe on December 14 (the actual moonset timing is progressively later the further south you are), giving mostly dark skies for all observers, especially those in the northern hemisphere. The Geminid radiant culminates around 2h local time, but well north of the equator it rises around sunset, and is at a usable elevation from the local evening hours onwards, while in the southern hemisphere, the radiant appears only around local midnight or so. Even from more southerly sites, this is a splendid stream of often bright, medium-speed meteors, a rewarding sight for all watchers, whatever method they employ. The peak has shown slight signs of variability in its rates and timing in recent years, with the more reliably-observed maxima during the past two decades all having occurred within 2h20m of the time given above. The main predicted timing, coupled with moonset, favours places from central Asia eastwards across the Pacific Ocean to Alaska. An earlier or later timing would extend this best-visible zone some way eastwards or westwards respectively. Some mass-sorting within the stream means the fainter telescopic meteors should be most abundant almost 1 of solar longitude (about one day) ahead of the visual maximum, with telescopic results indicating such meteors radiate from an elongated region, perhaps with three sub-centres. Further results on this topic would be useful. Coma Berenicids (COM) Active: Maximum: ZHR = Radiant: Radiant drift: v = r= TFC: December 12 January 23 December 20 ( = 268) 5 = 175; = +25 see Table km/s 3.0 = 180; = +50 and = 165; = +20 before 3h local time = 195; = +10 and = 200; = +45 after 3h local time ( > 20 N)
, : Coordinates for a shower's radiant position, usually at maximum. is right ascension, is declination. Radiants drift across the sky each day due to the Earth's own orbital motion around the Sun, and this must be allowed for using the details in Table 6 (page [add page number]) for nights away from the listed shower maxima. r: The population index, a term computed from each shower's meteor magnitude distribution. r= 2.0 2.5 is brighter than average, while r above 3.0 is fainter than average. : Solar longitude, a precise measure of the Earth's position on its orbit which is not dependent on the vagaries of the calendar. All are given for the equinox 2000.0. v: Atmospheric or apparent meteoric velocity, given in km/s. Velocities range from about 11 km/s (very slow) to 72 km/s (very fast). 40 km/s is roughly medium speed. ZHR: Zenithal Hourly Rate, a calculated maximum number of meteors an ideal observer would see in perfectly clear skies with the shower radiant overhead. This figure is given in terms of meteors per hour. Where meteor activity persisted at a high level for less than an hour, or where observing circumstances were very poor, an estimated ZHR (EZHR) is used, which is less accurate than the normal ZHR. TFC and IFC: Suggested telescopic and stillimaging (including photographic) field centres respectively. is the observer's latitude (< means south of and > means north of). Pairs of telescopic fields must be observed, alternating about every half hour, so that the positions of radiants can be defined. The exact choice of TFC or IFC depends on the observer's location and the elevation of the radiant. Note that the TFCs are also useful centres to use for video camera fields as well.
UKW-Nachrichten Italien / RSM / Vatikan / Malta
Redaktion: Luigi Cobisi, Via delle Mantellate 1/A, 50129 Firenze, FAX: 0039-e-Mail: firstname.lastname@example.org Italien Virgin Radio Italia Seit 12. Juli um 12.00 Uhr luft Virgin Radio ber die Frequenzen von Play Radio. Der RDS-Name wurde inzwischen umgendert in _VIRGIN_. Der PI-Code ist 5241. Ein Abkommen zwischen Finelco (Radio 105, RMC, RMC2) und Virgin Group hat den Einstieg Virgins in Italien erlaubt. Programmen sind natrlich alle auf Italienisch und werden in Mailand produziert. Das Format ist aber dasselbe des Londoners Senders. Play Radio wurde vor einige Monaten von RCS Medien Gruppe (Corriere della Sera) an der Finelco verkauft. Frequenzen auf http://www.virginradioitalia.it/. Piedmont Aus Turin sendet Radio Veronica One (Adr.: Via Massena, 60 - 10128 Torino, Tel. (+39) 011.5812111 - Fax (+39) 0115812119 - E-mail: email@example.com) mit weiter Deckung der Piedmont und Aosta-Tal Regionen und teilweise Ligurien. Auf der Karte die Frequenzen.
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