19-11-2018, 02:11 PM
(This post was last modified: 19-11-2018, 02:17 PM by ppppenguin.)
You don't really need to drive the X axis, just output a pulse to sync the scope's timebase.
Direct RF sysmthesis is great for Band I but will be much harder for Band III where an ultrafast DAC and very high speed clocks will mean it's all much harder and more expensive. I don't know what commercially available SDR kit does, either on TX or RX but at the low cost end it certainly can't be ultrafast ADCs and DACs. One way is to use a frequency changer, superhet style. Another way, though I don't know the detailed mechanics of it, is undersampling. The sample rate need only be twice the bandwidth of the wanted signal, not twice the carrier frequency. I've seen and undestood the maths for this but don't know about how you'd do it in practice, especially for a TX.
I'm getting rather out of my field here and haven't even done basic research on the subject yet.
Had a quick look and found articles like these:
https://www.digikey.co.uk/en/articles/te...ined-radio
https://www.analog.com/en/analog-dialogu...rizon.html
https://uk.farnell.com/sdr-radio-applications
Looks like up/down conversion is a common approach. AD's stonking new RF DAC is pushing the art to new heights.
Direct RF sysmthesis is great for Band I but will be much harder for Band III where an ultrafast DAC and very high speed clocks will mean it's all much harder and more expensive. I don't know what commercially available SDR kit does, either on TX or RX but at the low cost end it certainly can't be ultrafast ADCs and DACs. One way is to use a frequency changer, superhet style. Another way, though I don't know the detailed mechanics of it, is undersampling. The sample rate need only be twice the bandwidth of the wanted signal, not twice the carrier frequency. I've seen and undestood the maths for this but don't know about how you'd do it in practice, especially for a TX.
I'm getting rather out of my field here and haven't even done basic research on the subject yet.
Had a quick look and found articles like these:
https://www.digikey.co.uk/en/articles/te...ined-radio
https://www.analog.com/en/analog-dialogu...rizon.html
https://uk.farnell.com/sdr-radio-applications
Looks like up/down conversion is a common approach. AD's stonking new RF DAC is pushing the art to new heights.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
