[HamWAN PSDR] is -76dBm a strong enough signal?

Tom Hayward tom at tomh.us
Tue Sep 4 07:19:26 PDT 2018


On Tue, Sep 4, 2018 at 1:51 AM Edward Cukiernan <ecukierman at gmail.com>
wrote:

> Hi all, I was hoping to ask a question on if I should expect to be able to
> connect to hamwan. The short version is that I am using a Mikrotik BaseBox
> 5 RB912UAG-5HPnD-OUT, and I can occasionally get a connection, but it
> usually only lasts a couple of minutes and disconnects. When I am connected
> my status looks like this:
>
>                   status: connected-to-ess
>                  channel: 5880/5/an
>        wireless-protocol: nv2
>                  tx-rate: 10.8Mbps-5MHz/1S/SGI
>                  rx-rate: 9.7Mbps-5MHz/1S
>                     ssid: HamWAN
>                    bssid: 4C:5E:0C:8B:0D:70
>               radio-name: K7WAN/ETiger-S3
>          signal-strength: -76dBm
>      signal-strength-ch0: -76dBm
>       tx-signal-strength: -75dBm
>   tx-signal-strength-ch0: -90dBm
>   tx-signal-strength-ch1: -75dBm
>              noise-floor: -125dBm
>          signal-to-noise: 49dB
>                   tx-ccq: 49%
>                   rx-ccq: 56%
>    authenticated-clients: 1
>         current-distance: 29
>                 wds-link: no
>                   bridge: no
>         routeros-version: 6.41.3
>
> The things I was wondering about.
>
> 1) Any idea why I am seeing tx-signal-strength-ch0 being so much worse
> that tx-signal-strength-ch1? doesthis mean I don't have my antenna in the
> right orientation to match the polarization on tiger?
>

It could be that the second polarization is not enabled on your modem. Try
this command and then take a look at the signal strengths again:

/interface wireless set wlan1 rx-chains=0,1 tx-chains=0,1


> 2) Is it a problem that I am running an old version of router os? I see I
> am running 6.37.1, but the sector is running 6.41.3
>

That's a problem, but unrelated to signal strength. Older RouterOS versions
have security bugs. You should upgrade. I would start by upgrading
firmware, then RouterOS, then see if a new firmware is available with the
new RouterOS version:

Firmware upgrade:
/system routerboard upgrade
/system reboot

RouterOS upgrade:
/system package update install

Firmware upgrade:
/system routerboard upgrade


> 3) Any idea why I see to signal strengths for tx, but just one for rx?
>
> 4) sometimes I see a noise floor of -105, which obviously lowers my snr.
> Is this an indication that something is causing interference?
>

-105 dBm is still a decent noise floor. It shouldn't be a problem.

-76 dBm should be plenty for a consistent signal. Once you take care of
these little things, keep an eye on it to see if it continues to be
intermittent. Maybe there is another problem somewhere.

Tom
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