BH Problems


We have two CMMII modules with 5.7 AP’s and and are trying to set up a 2.4 back haul between the two. I have one set to master and one set to slave. On the slave I see 1500 RSSI and 2-4 on the Jitter but the units will not register. I have tried all the frequencies, made sure the color code is the same. No Joy

My question is should I set the BH master and the slave to Sync to Received Signal (Timing Port) and connect both GPS cables into their respective switchs?

I am confused about what the Timing Slave is doing to my CMMII. Since the CMMII has a gps reciever, I set the AP’s on that cluster to Sync To Received Signal. What does the Timing Master and Timing Slave control, just themselves or are they also controlling the CMMII as well.


The BHM should be set to receive signal (timing port) when using a CMMII. Your BHS will get its timing from the BHM so there is no need to set the receive timing on the slave end. You will only need the GPS cable at the BHM side.

The GPS inside the CMMII is controlling the timing for your environment. The AP’s and the BHM will get the timing from the GPS when plugged into the CMMII and set for receive signal (timing port).

Are you using reflectors on the 2.4 BH link?

Hi, thanks for the help.

Yes we do have reflectors on both ends. We have a lot of interference at the sites. Doing a spectrum analysis shows all channels in the 2.4 BH range at areound 60dbm. I am not sure but this may be the problem.

When I choose Enable Alignment Mode I can and see the mac address of the master and an RSSI of around 1500 with Jitter at 2-4, but I can’t register. When I flip the BH and Slave and choose Enable Aiming Mode, I show 0 RSSI??
If I select RSSI Only Mode and choose the correct frequency, I see about 60dbm. I think this must be signal from other transmitters on the site???

I did have the GPS cable from the Slave plugged into the CMM. I thought this might be the problem with registering. The documentation does not address this IMHO.

Another problem I noticed today was that the GPS status at both sites were showing bad voltage or low votage warnings. I searched thru your FAQ and found out that we may have a bad cat5 cable end or something. We are addressing this as well. Do you think that having the Slave GPS cable plugged into the switch could cause these errors?

Thanks again

By default, the tx freq is NONE. Keep this in mind.
For 5G cluster why do you want to use 2.4G backhaul?
Have you tried your backhaul in office on table? (without interference)

They work on the bench and a Motorola Business Development manager came out advised us to use a 2.4 bh at the site.


Hmmm… Are you sure, that 2.4 will give enough thruput between your sites?
I highly recommend to use 5GHz BH(or BH20) if available on different band, like 5.3

My Bad, we are using a BH20 at 2.4ghz

I Am facing the Same problem My 5.7 BH is not registering i m not using any GPS cable.
It wes working all fine for 3 days then all of the sudden i lost the conectivity.
on Salve i see the Registering status but it keep on this status and didnt get registerd.
I despratly need Help any one out there who can help me Out it.


saud hassan