thegriff
Member
In the nine months or so I've been messing around with decode of my local P25 system I've noticed what I think to be a transmitter related issue.
That is some frequencies decode better within DSD+ than others. I can get the correction value for my TXCO dongle darn near perfect but ultimately some frequencies within the range just won't decode all that well. Tonight I noticed Unitrunker's new "window value" does increase with some frequencies more than others.
Some examples:
851.61250 decodes well, 852.31250 does not
855.51250 decodes well, 856.36250 does not
I don't know whether there's an acceptable drift for transmitters but it seems the dongle correction is not tuned as well as I think or the transmitter may have an error factor itself.
Assuming the latter, how would I go about fixing this sort of variable drift? I was thinking I could sit down and manually adjust each frequency within UT's interface until I get the actual frequency. For example maybe 852.31250 needs to be adjusted to 852.31000.
With over 20 frequencies in my local system this method would take quite a while so I was wondering if there's a better way to figure out if there is a transmitter issue for certain frequencies and what sort of variances I should add/subtract to make things go quickly.
FWIW, my voice receiver has a TXCO and is 820T2 based. I've also noticed similar issues on my PRO-668 so I don't think it's dongle tuning but I'm no radio tech.
TIA!
That is some frequencies decode better within DSD+ than others. I can get the correction value for my TXCO dongle darn near perfect but ultimately some frequencies within the range just won't decode all that well. Tonight I noticed Unitrunker's new "window value" does increase with some frequencies more than others.
Some examples:
851.61250 decodes well, 852.31250 does not
855.51250 decodes well, 856.36250 does not
I don't know whether there's an acceptable drift for transmitters but it seems the dongle correction is not tuned as well as I think or the transmitter may have an error factor itself.
Assuming the latter, how would I go about fixing this sort of variable drift? I was thinking I could sit down and manually adjust each frequency within UT's interface until I get the actual frequency. For example maybe 852.31250 needs to be adjusted to 852.31000.
With over 20 frequencies in my local system this method would take quite a while so I was wondering if there's a better way to figure out if there is a transmitter issue for certain frequencies and what sort of variances I should add/subtract to make things go quickly.
FWIW, my voice receiver has a TXCO and is 820T2 based. I've also noticed similar issues on my PRO-668 so I don't think it's dongle tuning but I'm no radio tech.
TIA!
