RFM69HC Range Problem

[mrmin24]

Hi,

I am unable to get proper reception between two RFM69HC modules. The best RSSI I can manage is -65 with two modules sitting right next to each other. Max range 5 meters.

Each module has a quarter wavelength wire antenna and is powered via a 3.3V breadboard power supply - different power sources give same results. I even tried half wavelength antenna but this made things worse.

I am using the standard RFM69 library config  - 915MHz

Is there something obvious I am missing?

Thanks.

[TomWS]

Hi,

I am unable to get proper reception between two RFM69HC modules. The best RSSI I can manage is -65 with two modules sitting right next to each other. Max range 5 meters.

Each module has a quarter wavelength wire antenna and is powered via a 3.3V breadboard power supply - different power sources give same results. I even tried half wavelength antenna but this made things worse.

I am using the standard RFM69 library config  - 915MHz

Is there something obvious I am missing?

Thanks.

In your code, did you define isRFM69HW?  I know you're using the HC, but to use this device you need to define this constant.

Tom

[Felix]

mrmin24,
What hardware are you using (that you connect the RFM69HCW to)?

[mrmin24]

Thanks TomWS, will give it a try (I think I might have previously, but will try again).

Felix - The gateway is running on an UNO and is connected via level converter. The Node is running on a 5V pro-mini also via level converter.

Thanks thus far

[mrmin24]

OK!! TomWS your suggestion made a big difference. RSSI is now -35 when radios are close to each other and -67 at about 20m through a couple of walls.

I was still expecting better than that, but I have no baseline to compare. Can you maybe comment on what I should expect?

Thanks

[TomWS]

OK!! TomWS your suggestion made a big difference. RSSI is now -35 when radios are close to each other and -67 at about 20m through a couple of walls.

I was still expecting better than that, but I have no baseline to compare. Can you maybe comment on what I should expect?

Thanks

These numbers look ok although 'close' together I would expect RSSI values in the -20s, but, bear in mind, the RFM69 has a very wide range AGC circuit so even -67 is going to give you good signal quality.  I'm assuming that you've trimmed the antenna wires to the proper length... 

What is your transmit power level set to?

Tom

[mrmin24]

Yes, I see that on the node the RSSI when radios are close together is about -10, but the gateway still -35. I did however test up to about 50m and still had RSSI -70 on gateway through multiple walls, so I am happy for now. I will play around with the power settings as I go along. At the moment they are default.

Antennas are 78mm for 915MHz, so... I think this is right

Thanks again for the replies Tom.