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cariboulabs / cariboulite

CaribouLite turns any 40-pin Raspberry-Pi into a Tx/Rx 6GHz SDR
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Sampling rate limited to 4MS/s only in soapy_api #96

Closed hudouseko closed 1 year ago

hudouseko commented 1 year ago

Method Cariboulite::setSampleRate as defined in https://github.com/cariboulabs/cariboulite/blob/main/software/libcariboulite/src/soapy_api/Cariboulite.cpp ignores requested sample rate and always sets it to 4MS/s. Correspondingly method Cariboulite::getSampleRate always returns 4000000 (as 4MS/s). Nevertheless device itself supports multiple sample rates from 400kS/s up to 4MS/s, see clause 6.1.5.2 RFn_TXDFE - Transmitter TX Digital Frontend of the AT86RF215 datasheet here: https://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-42415-WIRELESS-AT86RF215_Datasheet.pdf. It seems that rest of the code is ready to support all sampling rates, while soapi_api is hardcoded for 4MS/s only.

edegraaff commented 1 year ago

BTW if i change sample freq in openwebrx and change the sample freq to above or below 4 MS/s it is as if i tune up or down the speed of the sound like the pitch of a pick-up

meexmachina commented 1 year ago

The sampling frequency is limited only by SoapyAPI. firmware and c API supports different sampling rates. but in the lower sampling rates (under 800 KSPS) an issue exists in the kernel module. It gets a read sample timeout while waiting for new batches of samples.

meexmachina commented 1 year ago

The different sampling rates are available in Soapy as well now.