0ffset on transmit frequency

classic Classic list List threaded Threaded
8 messages Options
Reply | Threaded
Open this post in threaded view
|

0ffset on transmit frequency

Don_m5aky
This post was updated on .
I have the following setup:-

Quisk 4.1.15 with Raspberry Pi, Softrock 6.1 and Startech 7.1 usb soundcard.

When I operate the PTT or Spot I get a strong carrier on the frequency that I set, checked on a counter and a receiver, but when I speak into the mic and listen on a nearby receiver the sound comes out on whatever the centre frequency is on the graph, not that selected, although the Softrock is receiving on the correct frequency. As far as I can see my configuration is correct but perhaps I have missed something.
Any advice would be much appreciated.

Another question, is there a procedure for setting up the rx and tx amplitude and phase? So far I haven't found any info on this.

Regards
Don m5aky
Brsitol UK  
Reply | Threaded
Open this post in threaded view
|

Re: 0ffset on transmit frequency

ahlstromjc
Administrator
Hello Don,

I will check the transmit tuning. The amplitude and phase adjustments are on the Config/Config screen.

Jim
N2ADR
Reply | Threaded
Open this post in threaded view
|

Re: 0ffset on transmit frequency

Don_m5aky
Hello Jim,
Thanks for the reply.
I have found the adjustments but I'm not sure how to use them.
Don
Reply | Threaded
Open this post in threaded view
|

Re: 0ffset on transmit frequency

Don_m5aky
A bit more info.
I've rigged up an RTL dongle on another computer.
With the cursor on 3.70 MHz the carrier is coming up on that frequency and I can see double sideband  AM audio without any apparent carrier on 3.695, which in this case is the centre frequency.
Don
Reply | Threaded
Open this post in threaded view
|

Re: 0ffset on transmit frequency

ahlstromjc
Administrator
Hello Don,

I am not able to verify the transmit offset. But my hardware is a SoftRock RxTx with firmware 15.12.

Please connect a headphone to the line out of your sound card, and listen to the output of the Spot button. It should be a pure sine wave at a frequency equal to the difference from the Quisk center frequency. That is, zero hertz at the center frequency and increasing as you tune away from center.

Then try the same thing while transmitting USB. You should hear your voice at the center frequency, but the voice should go up in pitch as you tune away from center. Let me know what you hear.

Jim
N2ADR
Reply | Threaded
Open this post in threaded view
|

Re: 0ffset on transmit frequency

Don_m5aky
Hello Jim.
With the headphones and  Spot I can hear zero beat on the centre frequency, increasing as I go  further away.
However in lsb transmit I can hear nothing in the headphones.
I am using the Pulse default device for Microphone Capture and Line for PCM Capture.
As it is, but with the headphones out and the connection to the softrock back in, I can still hear the audio on a nearby receiver on the centre frequency even though I have selected a frequency that is 15 or 20kHz away from the centre.
Don
Reply | Threaded
Open this post in threaded view
|

Re: 0ffset on transmit frequency

ahlstromjc
Administrator
Hello Don,

Your microphone is not working. Look at the Config/Status screen and check the mic level. Use the pavucontrol program to check the pulse audio system.

Jim
N2ADR
Reply | Threaded
Open this post in threaded view
|

Re: 0ffset on transmit frequency

Don_m5aky
Hello Jim
Thanks for the help. I think I am now making progress.
I have made changes to the microphone capture in the config menu and can now hear the ssb with the headphones as you describe.
I changed the capture from Line to Mixer in the audio settings and it appears  I am  now receiving and transmitting on the correct frequency albeit with a bit of echo accross the shack.
I will report back after more tests.
Don m5aky