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Question on RF distance with 900Mhz  XML
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john



Joined: 22/02/2016 04:59:25
Messages: 2
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I have several RFM95W miniwireless units and all are having the same issue with poor RF distance at 900Mhz. I have soldered on a copper 82mm "whip" antenna but cannot pass packets further than 1 meter away. I am testing with the example RadioHead sketches for rf_reliable_datagram_(client|server) with the following exceptions:

driver.setFrequency(925.00);
driver.setTxPower(20, true);
driver.setModemConfig(RH_RF95::Bw125Cr45Sf128);

I've tried setting the setTxPower as low as 10 and as high as 20. On the server side I display the RSSI like so:
Serial.print(driver.lastRssi(), DEC);

However, I'm only seeing between -80 and -85 when I should expect to see something around -50 at 1 meter range. I've also tried soldering on RP-SMA connectors with an actual 900Mhz antenna but see a decrease in performance there (same range, worse RSSI).

I'd really like to do some range tests but I can't even get past 1 meter. Any ideas?

Thanks,
John

This message was edited 2 times. Last update was at 21/03/2016 08:20:55

john



Joined: 22/02/2016 04:59:25
Messages: 2
Offline

Found the fix. I had set the power incorrectly based on the module I had.

Here's what was needed:
driver.setTxPower(20);
Rick



Joined: 30/05/2014 22:08:56
Messages: 93
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Hi John,

Thanks for your input and for letting customers know of your resolution.
I changed the title from: "Poor RF distance..." to "Question on RF distance...",
reason being, these devices have excellent RF distance, and such a title could mislead customers to think otherwise.

Best Regards,
Rick
 
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