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M0LTE / pi-transceiver

An attempt to build a complete ham radio transceiver around a Raspberry Pi
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Forward and reflected power meters + SWR display #21

Open M0LTE opened 2 years ago

M0LTE commented 2 years ago

For measurement of forward and reflected power we need at least two channels of ADC. The Pi has none, but it does have I2C.

Purchased an ADS1115 I2C 4 channel 16 bit ADC to trial. This should be easy to bring into the UI.

@G4CDF What voltage range do we need to measure? Potential divider with a pot sufficient to calibrate?

G4CDF commented 2 years ago

The output from the detectors will be amplified. So say 0v to 3V at full power? I would do all the cal in software.

M0LTE commented 2 years ago

Maybe just a 10k pot in series to be able to fit the whole of the sample into the range of the ADC board. The board will have a hard maximum, can’t do that in software. 3V gives me a ballpark to aim for.

On Mon, 10 Jan 2022 at 13:54, Mike @.***> wrote:

The output from the detectors will be amplified. So say 0v to 3V at full power? I would do all the cal in software.

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G4CDF commented 2 years ago

I would expect to be able to design the power detector such that the saturated power of the PA would not exceed the 3V limit (assuming that the ADC runs on 3 V). With 16 bits in the ADC there should be no need to have a trimmer on the PCB.

M0LTE commented 2 years ago

Great, there’s your requirement then :-)

I’ll let you know how I get on with that ADC board

On Mon, 10 Jan 2022 at 15:40, Mike @.***> wrote:

I would expect to be able to design the power detector such that the saturated power of the PA would not exceed the 3V limit (assuming that the ADC runs on 3 V). With 16 bits in the ADC there should be no need to have a trimmer on the PCB.

— Reply to this email directly, view it on GitHub https://github.com/M0LTE/pi-transceiver/issues/21#issuecomment-1009005294, or unsubscribe https://github.com/notifications/unsubscribe-auth/AJAQNWFA2NLD2BF3JULIDLTUVL4VXANCNFSM5LTSW75A . Triage notifications on the go with GitHub Mobile for iOS https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675 or Android https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub.

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