PTP650 Dual Payload

Hi Guys,

We are replacing Ubiquiti Powerbridge links with Cambium PTP650 links with the Full Licence on them.

We have attempted to deploy our first PTP650 link but failed as it had very poor connectivity.  I am seeking a little help getting started with the Cambium product line.

Terminology question
Dual Payload - Does this mean dual polarity as in V+H?  Or does it have another meaning?

Max receive modulation mode and lowest Ethernet modulation mode.
Why is it that the "Max Received Modulation Mode" is lower than the highest option in the "Lowest Ethernet Modulation Mode"?

It seems that the "Max Receive Modulation Mode" is 256QAM 0.81

and highest setting for the "Lowest Ethernet Modulation Mode" is 256QAM 0.81 (DUAL)

Signal Strength

Is the live signal strength of the link shown on the far right of the Received Power line under "Status" in the GUI?

Receive Modulation Mode Detail

How do I get a better insight as to the "Receive Modulation Mode Detail" messages and what they tell me.

Message 1 "limited by the wireless conditions "
Message 2 "Restricted Because Of Byte Errors On The Wireless Link"

Thanks in advance guys


Glad to hear you're installing PMP650 bit sorry to hear you're having some issues!

Please find some explanation below on your queries:

Dual payload:

Cambium refer use the term dual payload to indicate two different data stream are carried by the H and V polarizations. In single stream mode, the same data is sent over both the H and V polarizations. The PTP650 will assess the propagation channel to determine if dual payload can be supported.

Max receive modulation mode and lowest Ethernet modulation mode:

The max receive modulation the user can set does not specify whether it is single or dual payload. The reason for this is that dual payload is not always available due to the wireless propagation condition, so the decision to use either single or dual is left to the radio algorithm, rather than the end user.

Alternatively, the lowest Ethernet Modualtion Mode is to be used by the user to define whether the link capacity is worth having at all (For example, in some networks, having less than say 10 Mbits/sec is not worth as this would not support the wanted service). As the single dual payload result is very differnet link throughput, the radio needs the user to specify which is acceptable.

Signal Strength

On the Status page, the information shown for the receive power (and a few other parameters) are respectively the min, mean, max and latest value. The right most one does show the most recenet measurement.

Receive Modulation Mode Detail

"Limited by the wireless conditions": the signal-to-noise ratio is too low for the radio to use a higher modulation mode. This maybe due to the receive signal being low or the noise level in the channel being high.

"Restricted Because Of Byte Errors On The Wireless Link": the signal-to-noise ratio would be high enough for the radio to use a higher modulation mode but this is prevented because errors are being detected. The errors may be caused by high level burstly interference within the channel.

I hope this helps, let us know if not!

Good luck with the PTP650 installation,

Antony J.