Putting AP on FM radio broadcasting tower

shielder · Fri Jun 09, 2006 2:20 pm

Has anyone ever tried putting AP on FM radio broadcasting tower? Will it interfere each other?

Fri Jun 09, 2006 2:21 pm

basically the frequencies are completely different, so there should be no problems.

shielder · Fri Jun 09, 2006 2:24 pm

I feel the same way too, but i found out a very weird condition. Whenever the FM radio is not broadcasting, my client could get -70, but when the radio is broadcasting, my client signal would drop to -85 or more, but the latency is still good as i could ping my client on 2-5ms.

enrique · Fri Jun 09, 2006 2:40 pm

shielder,

Try to move a couple of meter your client´s unit away from the FM tower. and see how it goes.

Regards

jonbrewer · Sat Jun 10, 2006 2:40 am

basically the frequencies are completely different, so there should be no problems.

Yes, the wireless transmission frequencies are completely different, but the system board and Ethernet links will be heavily interfered with if the FM station uses high enough power.

Also to consider is that since the Mikrotik RB532 AP units are in a plastic box with no shielding, and some of the components aren't very high quality, the system boards can cause interference with other radio communications equipment.

GotNet · Sat Jun 10, 2006 7:06 am

Scary things happen up there. Watch bands, metal glasses and belt buckles get hot. Switching (tx/rx) stuck on. Very bad for the POE (on board ~48 to 12) power supplies.

Mike

maxfava · Mon Jun 12, 2006 11:25 am

Hi,
using the shield covering all the box containing the RB with the minipci module in external environment, could create hot issue? Take in care that I want to use RB 532 where the maximum external temperature is 42 °C.
Any experience?

djape · Mon Jun 12, 2006 12:29 pm

I have 2 installations on FM radio towers.
On both installations I have the same issue as shielder, when radio is off i have 10db better signals then when it on. On one installation where FM radio is using 2KW booster I can't make atheros to work at all, tried all known atheros cards, sr2 too. Prism cards work like a charm! Must be a great difference in noise sensitivity. On other installation I couldn't use omni at all, so I use sector horizontal antennas.

Working solution = sector hor. antennas and prism cards.

Cheers all...

g3 · Mon Jun 12, 2006 5:06 pm

I have 2 installations on FM radio towers.
On both installations I have the same issue as shielder, when radio is off i have 10db better signals then when it on. On one installation where FM radio is using 2KW booster I can't make atheros to work at all, tried all known atheros cards, sr2 too. Prism cards work like a charm! Must be a great difference in noise sensitivity. On other installation I couldn't use omni at all, so I use sector horizontal antennas.

Working solution = sector hor. antennas and prism cards.

Cheers all...

I have the same problem in a FM radio tower with 1kw. I can't make atheros to work well.
What prims card do you use? is minipci?

djape · Mon Jun 12, 2006 5:09 pm

its PCMCIA with PCI adapter...

BulleriNET · Tue Jun 13, 2006 6:10 pm

i have the chance off useind a fm tower now i do not know if i will is the interferace with just 2.4 or will it be in the 5ghx band to i am useing a metal box with 2 532 boards and all sr5 cards will this get past it or do i need to look else where??

Giepie · Tue Jun 20, 2006 6:53 am

I also experienced similar conditions on 2-way radio towers. We used WRAP boards at first, but when we installed RB500's, the RF guys complained about us interfering. We were lead to believe that the RB500's causes an induction (magnetic field) around themselves.

I haven't tried it, but perhaps it will make a difference if you install the RB's inside a metal enclosure. Electronically this makes sense, perhaps someone would like to try it.

Keep us up to date!

PS, I have very bad experience with Prism miniPCI cards, but EXTREMELY good experience with PCMCIA Prism cards... Just my experience

spok · Thu Jun 22, 2006 12:57 am

Use Djape metal outdore box for routerboard.
Use outdore ftp cable (for power & ethernet)
Do not use omni antenas.
Do not put your antena near FM antena. ( 2m- 4m below)
Grund it evrenting!!!!!

jober · Thu Jun 22, 2006 4:02 am

If I was going to set up a test I would start with LMR900 ran up to a 90* sector and then use a rb532 with a SR2 in a metal box.

There is no way I would go up a FM or AM tower. Some of these things will cook you.

mykrosoftz · Fri Jun 23, 2006 2:58 am

I have a atheros config running with no problems in the same room with a fm broadcast. I'm using a regular pc with a metal case and i have regular noise when the fm radio is on. I had found no problems running using atheros config (with a regular pc) in the same room with a fm broadcast.

Putting AP on FM radio broadcasting tower

Putting AP on FM radio broadcasting tower

AP and FM

looking at doing this