How does a receiver compensate for frequency deviation?

[jonwienke]

Ugh, my dyslexia is catching up with my alzheimer's.

 

[paulears]

Jonwienke - yes, sorry, I did miss it. Let's face it, these cheapo SDRs are really so compromised in their technical performance that while being an excellent 'revealer' of activity, frequency stability isn't their primary job, which was to receive TV signals that were many MHz wide, where a few Hz one way or the other is immaterial.

In a way, this is just a good example why jurisdictions world wide set standards for radio comms. The idea of software defined radios doesn't have to mean poor stability or filtering, as there are some very expensive and excellent ones as mentioned above, but the performance of many, makes the usual posts of how terrible Baofeng and others are look a bit silly, when in comparison with cheap SDRs, they are excellent!

 

[jonwienke]

Do the radio makers still use PLL (Phase Lock Loop) chips in conjunction with a VCO (Voltage Controlled Oscillators) to handle frequency stability?

In general, no, unless you're running single sideband and dialing the freq to within a few Hz is necessary to get the voice to sound right. For FM, if you have a reference oscillator stable to within 1-2PPM, then there's no real need for the VCO.

 

[jonwienke]

Jonwienke - yes, sorry, I did miss it. Let's face it, these cheapo SDRs are really so compromised in their technical performance that while being an excellent 'revealer' of activity, frequency stability isn't their primary job, which was to receive TV signals that were many MHz wide, where a few Hz one way or the other is immaterial.

I got one ot the RTL-SDR sticks with the 1PPM TCXO. I don't expect stellar performance from a $20 USB stick, but they are useful for viewing band activity and finding signals.