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A week later and there is something wrong
27 November 2012 | by At the back end of last week I set Faros off and running to listen into the various NCDXF beacons.
All is not well
The set up of rig, Signalink, sound card (either as a usb or internal) is inconsistent at best and not hearing anything at all at worst. After a few days of twiddling and mucking about I am at a loss. I’ve never really got the thing going with my ft817 and frankly don’t want to spend a whole heap of time trying to sort it out. Perhaps I’ll go back to it once I’ve had a chance to think about it a bit more.
Here’s what’s stumping me:
Computer – More powerful than the one it used to run off 24/. Both internal and usb sound cards have failed to get any signals. in fact the usb sound card made the software act very oddly. Audio in directly from the rig…no difference. Adjusting the volume makes no observable difference.
Rig – CAT OK, timing OK, audio out OK
The software is reporting 100% QSB which I don’t recall from the last set up so I can only surmise that it doesn’t like the two options for the sound card. Time to take a break from it.
4 Responses to “A week later and there is something wrong”
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Hi Alex,
I may be wrong, I often am, but I think you need to feed the received audio via an external cable, it’s not available via the data port on the ‘817. If that’s not the problem then maybe it’s the mode setting needs to be a digital mode rather than just SSB or USB. I forget the modes available but I think it will be something like ‘User USB’.
Two things which have both tripped me up in the past!
73 Stuart
The audio has come through either the signalink or speaker out. Th elevels are very low (Faros needs low audio levels) and I’ve checked that something is getting through with a sound recorder program but no luck so far.
I noticed yesterday I had the ‘Force CW’ mode ticked so will try that.
73
Alex
I would try a couple of things:
– Using Spectran or Argo, tune in a time station on *AM*(WWV/H when conditions permit) and see if the audio tones are being displayed at frequencies that that should be (500/600 Hz.) If you have a known-accurate audio source other than WWV/H, that would be fine but don’t trust another computer unless you know that it’s dead-on! I’ve seen some sound cards that are as much as 8% off-frequency and *nothing* will decode with that much error if the absolute frequency is important. (e.g. most digital modes, narrow audio filters, etc.) A free “Audio oscilloscope” program (using the sound card) may also be useful if it can accurately measure frequency.
– After verifying that the audio sample rate is close to frequency within reason, tune in WWV/H (or another time station) 1 kHz low in USB to see that a 1 kHz tone is produced to verify that the radio is on-frequency: Some earlier ‘817’s had a defective reference oscillator that would put them way off frequency. If this were the case, you’d have probably spotted it long ago…
– See if you can decode anything at all with the sound card – say PSK31.
– For the benefit of some newcomers, there’s a “rookie” mistake where someone mistakes the RF carrier frequency for the dial frequency, forgetting to do the math – but that’s why many times (such as WSPR) the dial frequency is mentioned rather than the carrier frequency. (IIRC, this is one of the reasons why PSK31 ended up at 14071-14072-ish rather than actually clustered around 14070.)
– From another computer or source, generate a constant tone and see if it’s “continuous” – without glitches or breaks that would be apparent on the waterfall on Spectran/Argo. If audio samples are being dropped, it should be apparent as discontinuities in what would otherwise be a perfectly clean line on the waterfall.
– Spectran/Argo will also show whether the audio levels are too high or too low as will a number of free “audio oscilloscope” programs: Better to be a bit low than too high.
– The ‘817 has both RX and TX audio from the rear-panel accessory (mini-DIN) jack, but the TX PTT or TX audio will *only* work if in a “DIG” or “USER” mode in which case the front-panel mic audio is disabled. The RX audio levels are typically much higher than computer MIC-input audio and could distort badly if patched directly – and will likely require both attenuation and DC-blocking to knock down the levels and remove the microphone bias voltage if the MIC input is used. Don’t forget that the audio level from the ACC jack is fixed.
– While listening to a time station or checking with known-accurate time reference, make sure that the PC clock is very close to UTC. (Less important than for, say WSPR)
Best of luck and 73.
Thanks for all the pointers Clint. I certainly hadn’t thought about the frequency being ‘off’ as a potential cause.
One of the main issues I’ve found is the amount of noise from the netbook itself. Oddly it doesn’t come on right away, as soon as the pc is turned on. Only after a few 10’s of seconds. The noise levels increase dramatically from virtually nothing on some of the bands to s8 or 9.
The timing is done by gps so the pc clock is going to be as accurate as its going to be but Faros does have an offset facility and a tracker to show the movement of time, over time if that makes sense. The drift is minimal over the course of a day.
I suspect that the noise is the main issue now but I will certainly spend some time checking the audio and frequency as per your notes. Very helpful.
73
Alex