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--- packet:9k6-rig-support [2024/01/14 23:37] – [Conclusions] g7bcs
+++ packet:9k6-rig-support [2024/01/14 23:45] (current) – [Receive delay and setting time] g7bcs
@@ Line 39: / Line 39: @@
 I'm fortunate in having a fair bit of test equipment and, for the majority of the measurements and tests, I used a Rohde & Schwarz CMTA radiocomms analyser. This is a rather long-in-the -tooth "swiss army knife" for testing mobile radios and ideal for this application. It works in both RX and TX test modes. In the former, it can generate a signal at a confugred frequency and level, modulation with a defined deviation can be applied from either one or both of its internal audio generators or an external source, and it can analyse the corresponding demodulated audio from the radio. In TX test mode, it can generate audio for modulating the radio under test, and measure the frequency, transmit power, modulation depth and it can provide an output of the demodulated signal.
-One of the problems with "soft" TNCs such as the Nino and Direwolf is that you can't get to the signals needed to observe the "eye" and make a subjective check of whether a received signal is likely to be demodulated successfully. For these tests, I used an old G3RUH modem in test mode, where it transmits pseudo-random bits from its scrambler, to both generate a signal to modulate the R&S test set, and to recover the clock from the received signal from the radio under test to allow an eye diagram to be observed on an oscilloscope. 2.4 kHz deviation was employed.
+For some, mostly timing related, measurements at the RF interface I used a Rohde & Schwarz FSB spectrum analyser in Zero span mode, with sweep triggered by the PTT line fed into the rig.
+One of the problems with "soft" TNCs such as the Nino and Direwolf is that you can't get to the signals needed to observe the "eye" and make a subjective check of whether a received signal is likely to be demodulated successfully. For these tests, I used an old G3RUH modem in test mode, where it transmits pseudo-random bits from its scrambler, to both generate a signal to modulate the R&S test set, and to recover the clock from the received signal from the radio under test to allow an eye diagram to be observed on an oscilloscope. 2.4 kHz peak deviation was employed in all scenarios where a modulated signal was generated.
 ===== The Rigs =====
-The three rigs I tested were the Tait TM8200, an Icom IC-E208 and a Yaesu FT-7800. The latter two had both failed to perform at 9k6. The former is well proven to work flawlessly. I had previously also tried a Yaesu FT-817 on 9k6 packet, unsuccessfully, more to have another sample than anything else, but since this radio is limited to 5W TX power, and also uses relays to switch the signal path from RX to TX, I didn't proceed further with this rig, since 9k6 packet will never be its forte.
+The three rigs I tested were the Tait TM8200, an Icom IC-E208 and a Yaesu FT-7800. The latter two had both failed to perform at 9k6. The former is well proven to work flawlessly. I had previously also tried a Yaesu FT-817 on 9k6 packet, unsuccessfully, more to have another sample than anything else, but since this radio is limited to 5W TX power, and also uses relays to switch the signal path from RX to TX, I didn't proceed further with this rig, since 9k6 packet will never be its forte. All rigs were tested in the 70cm band, at a frequency of 432.625MHz.
 ===== The Measurements =====
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 The top trace shows PTT being released at the end of a transmission (the RX frequency already has a modulated signal present). Bottom trace shows the demodulated output arriving from the rig as it recovers.
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