Force 425 max xmt power lower at SM

I’m trying to configure an F425 link with AP as ePTP master, SM as ePTP slave, channel 5180 x 20. No matter what I do, SM xmt power is limited to +23 while AP is +28.

Why isn’t the SM also +28? Same hardware, and it seem the same FCC rules for PTP links would apply. Am I doing something wrong?

I would assume it’s related to the following fact:

Important to know difference between Tx Power shown on UI for AP and SM.

In general ePMP devices distinguish two types of traffic — data traffic and management traffic.

ePMP always try to send Data traffic on the highest possible MCS, Management traffic always uses MCS1 or MCS0(Configurable option on UI).

Becauses of this Tx Power for Data packets and for Management packets will be different.

Each AP may have several SMs registered on it.
Therefore it was decided that AP will indicate Tx Power of Management packets on UI and SMs will indicate Tx Power of all packets(Data + Management). AP communicates with all registered on it SMs and Data packets TX Power will be different for each of them. Only Data Tx Power transmitted with same value for all registered SMs.

Let me check exact numbers and get back to you with details tomorrow.

Thank you

Except Force 400c/425 only work in ePTP mode. The AP is ePTP master, the SM is ePTP slave.

Out of the box, an F425 is in SM mode. I tried changing the SM to AP mode, save and reboot, then changed it back to SM. Now it lets you select up to +30 dBm in the GUI and status shows +28 xmt power.

Kind of sounds like a FW bug.


Sounds like a bug in the UI for that section of web code.

I’m having all sorts of xmt power problems with this product. Doesn’t help that even the latest version of Link Planner has totally wrong numbers for the various sub bands.

At 5180x20 (or 5200 or 5220), the GUI lets me select up to 28 dBm xmt power and status shows it transmitting at +28, but the rcv level both directions is around 10 dB lower than in the 5.8 sub band e.g. 5865x20. The GUI says it can transmit at +30, but that’s only a 2 dB different, not 10 dB.

Is the actual xmt power lower than what the config and status show in the GUI? It’s hard to believe this is an antenna performance issue at the lower frequencies.

I know the FCC rules are complicated in 5 GHz with things like OOBE constraints, but if the GUI says the radio is transmitting at +28, I assume it is actually transmitting at +28.

Can you set center to 5825 at 20mhz. That is a +30db tx frequency (27db per radio, two chains).

There is a lot of problems with multiple radios with multiple radio streams when it comes to tx power per chain, but the short of it is the wider the channel, the more streams and thus less power per stream to keep within the conducted power limits.

Issue was identified and internal ticket is open. We will provide the firmware with the fix.
Still, @Ken_Hohhof , can you please attach techSupport files (Tools > Backup/Restore > Backup Technical Support File > Download) from master(AP) and slave (SM)?
Thank you.