Wireless Signal Strength

[Viper43]

Actually, I live in a rural area, not a whole lot of other RF type distractions. Other users with other phones see the vascilation so our curiosity piqued. Thanx

I'm in a rural area too, but there is a ton of RF floating around here.
1: farmers and their business radios
2: schools 5 within 5 miles with portables, all the buses
3: 4 cell towers within 5 miles (1 a block away)
4: 50+ amature radio folks
5: around 90 home computer WiFi systems
6: Public safety radios
7: a bunch of FAA towers for Indy and Chicago ATC
8: ILF for the local airport
9: All the other misc airport frequencies including ground
10: the Indiana State Police system
11: Eli Lilly Co. systems
12: a bunch of other manufactuer related systems
13: the power and telco systems (some meters are RF read at the offices on Electric)
14: Alarm and survellence systems (including my own)

And I could go on, you'd be amazrd at whats out there your not aware of, any or all of it can affect either cell phones or scanners, amature radios and so on.

V

 

[bwhite]

Gee Viper, you don't sound so rural when you paint that picture of your surroundings.

 

[slicerwizard]

Where do you get software like that and how do you hook it up to the fone?

Probably from the same places you get Motorola RSS and CPS. It works with the phone's regular data cable.

How do you learn what all those numbers and codes mean on the screan and software?

I guess you could ask on the right forums. howardforums.com or batlabs would be a good start.


From the first photo:

28.79 = SQE (signal quality estimate); It's based on RSSI and BER. Good numbers on that handset would be about 25 to 32. When it gets into the low 20's, the audio is crap.

0EB = current site control channel frequency index.

2 = color code used by current site. Color codes are used to differentiate sites that use the same carrier frequencies.


-00db = handset TX cutback. 0 = no cutback (e.g. full TX power). TX power is controlled by the control channel received signal strength; stronger control channel = less TX power needed to talk back to the site.

-91 = control channel signal strength. -90 isn't very good; -75 would be nice.

0 = TX timing advance. As you move away from a site, the handset has to send its inbound digital packets earlier in order to avoid walking over the user assigned to the next 15 ms time slot. IIRC, 0 = 0 to 5 miles from site, 1 = 5 to 10 miles from site, etc. Those numbers might be off a bit, but the granularity is somewhere between 5 and 8 miles.


+2 = PA temperature (Celsius); yes, it was cold out.

+0 = PA temperature change in last two seconds.

0 = TX power cutback due to PA overtemp. 0 = no cutback, 1 = 16% cutback, 2 = 33% cutback, 3 = 50% cutback.


From the second photo:

SU Link = subscriber unit (handset) serial data link. Green = serial data being received.

GPS Link = external GPS receiver connected to a second PC serial port. Red = no link.

GPS Track = GPS receiver 2D or 3D fix. Red = no fix.

GPS data is used in conjunction with RSSI and SQE readings to facilitate the creation of drive test based coverage maps and lists of dead spots.


CC/Carr = color code and control channel frequency index.

RSSI = control channel signal strength.

C/I = SQE.

SRVR = serving site (the current site).

FGxx = neighbour site with acceptable RSSI and BER. If the current control channel signal degrades sufficiently, the handset will switch to one of these neighbour sites.

BGxx = neighbour site with poor RSSI and/or BER. The handset does not want to register on any of these sites. Five of these sites are in the current site's neighbour list, but the handset cannot detect their control channel RF carriers. This is not unusual, since neighbour lists should not only list a site's immediate neighbours, but also the next ring of sites. This lets the handset find a distant neighbour site when an immediate neighbour site fails or is down for maintenance.


The handset continually monitors the SQE of the serving site and all neighbour sites and will try to use whichever site has the best SQE.

 

[bwhite]

You fired off another question that the Verizon folks cannot seem to answer, with your first line "28.79 = SQE (signal quality estimate); It's based on RSSI and BER. Good numbers on that handset would be about 25 to 32. When it gets into the low 20's, the audio is crap." Quite often, even with a good signal it is very difficult to understand the person talking to me on my G'zone phone, I'm now on my 3rd one since June. One of the techs says "sounds like a blown speaker", I don't use the thing much, surely not loud. Doesn't sound blown to me, just like it is rendering sound for 1/10th second then not, then yes, etc. If I use the earpiece it sounds fine. So with the "audio being crap" does that mean "yes, there's a carrier with voice data but there is no quality to the data?" Perhaps my case ?

 

[N_Jay]

SQE numbers are technology dependant. You can not compare iDEN (from teh example) with CDMA (Verizon).

These measurements are about the recovery of the signal from the RF carrier. If you have bad sound on speaker and good sound on headset, then it is a completely unrelated issue.

 

[gcgrotz]

Hey N_Jay and the others:

Just to follow-up all of your thoughts, part of my job is taking readings with a power meter on a CDMA system and, as you know, the power varies constantly with loading and how far away a mobile may be. On busy sites I see traffic-related power variations of 3 to 6 db typically. That is then multiplied by an antenna that may have (at 1900 anyway) 14db of gain. It is easy to see that this will cause a BIG variation in ERP.

This also doesn't account for the fact that unless you are way out in the sticks, those "bars" on the phone reflect signals from many towers. If you had a way to access a test mode screen, one thing you can see is a "neighbor list" showing how many potential towers your phone can hand-off to. Another test mode screen, which pretty much stays up all the time on my phone, shows actual rx/tx levels in dbm.

One last thing about CDMA is that it doesn't matter how much or how little signal you have, the main thing that determines call quality is the frame error rate, or FER. CDMA systems are designed to work at as low power as they can to keep the FER below a threshold.

So don't worry about the bars, unless it is one where your favorite bartender works.

 

[N_Jay]

Hey N_Jay and the others:

. . .

So don't worry about the bars, unless it is one where your favorite bartender works.

All true, except you have jumped to the conclusion that the bars are "Signal Level".

In reality the bars are (or should be) a measure of how likely it is that the the call will be of suitable quality.

The software in the phone is taking many factors into account when it adjusts the bars displayed. (Very similar to the signal quality measurements displayed in test mode).

 

[bwhite]

N_Jay,
On your last post, with you exactly.
I don't care how fine or strong the carrier signal is, If I can't flow data/voice over it the signal is worthless. That's kinda what I think my phone's bars are telling me.

Wow, post number 1,000 for me, I'll have to find myself a gold star.

 

[N_Jay]

Wow, post number 1,000 for me, I'll have to find myself a gold star.

I went right past 10,000 on another forum without noticing.

I never look at those numbers unless someone points it out.

 

[bwhite]

Ya, just have a way of "letting the air out of people's tires...."