# Thread: How to check Signal Strength

1. ## How to check Signal Strength

(A converged post for the FAQ from everyones contributions. Feel free to submit corrections.)

You can get a signal strength reading by issuing an AT+CSQ to the modem. You will get a number on a scale of 0 to 31 with 0 being worst (< -113db) and 31 (> -51db) being best.

To calculate the actual receive level, issue the AT+CSQ command to the card. Take the number before the ,99 and multiply it by 2. Subtract that figure from -113dBm and that will give you your signal reading in dBm.

For example, a value of 13 results in -113dBm - (13x2) = -87dBm

and 17 in -113dBm - (17x2) = -79dBm.

For those who need to START -> RUN -> CALC to figure this out, here's the easy way...

0 < -113 dBm
1 -111 dBm
2 -109 dBm
3 -107 dBm
4 -105 dBm
5 -103 dBm
6 -101 dBm
7 -99 dBm
8 -97 dBm
9 -95 dBm
10 -93 dBm
11 -91 dBm
12 -89 dBm
13 -87 dBm
14 -85 dBm
15 -83 dBm
16 -81 dBm
17 -79 dBm
18 -77 dBm
19 -75 dBm
20 -73 dBm
21 -71 dBm
22 -69 dBm
23 -67 dBm
24 -65 dBm
25 -63 dBm
26 -61 dBm
27 -59 dBm
28 -57 dBm
29 -55 dBm
30 -53 dBm
31 > -51 dBm

Marginal - Levels of -95dBm or lower. At these sort of levels, it is very likely that you may suffer low throughput and disconnects due to cell loading/breathing even with an outdoor antenna.

Workable under most conditions - Levels of -85dBm to -95dBm. Probably worth considering an outdoor gain type antenna. Could suffer poor throughput and disconnects due to cell loading/breathing.

Good - Levels between -75dBm and -85dBm - normally no problem holding a connection with this sort of level (even with cell breathing) without the use of an external antenna.

Excellent - levels above -75dBm. Should not be affected by cell breathing/loading and should not require an external antenna.

2. Originally Posted by vodacom3g
You can get a signal strength reading by issuing an AT+CSQ to the modem.
If you do not know how to issue the AT+CSQ command, here is more info on how to go about it.

1. Open Hyperterminal (normally found under "Accessories" and then "Communications" in HexP.
2. If you have not used Hyperterminal before and not configured "Dial-up Networking" it will pop up the dialling properties box where you can fill in the dialling code. After that it will open Hyperteminal and launch the New Connection Wizard.
3. On the first Wizard screen, type anything in the "Name:" block and click on OK
4. On the next screen, choose the datacard modem in the "Connect using" pull-down list and click on OK
5. Click cancel on the next screen and you should come up with a blank Hyperteminal window
6. Type AT and press "Enter" and modem should reply with "OK"
7. Fire away with the AT+CSQ command.

Follow directions in V3g's post to determine signal level.

Plus it should be remembered that you are measuring received signal level. You should aim to get it better but do not aim for perfection as received efficiency does not necessarily equate to radiated (transmitted) efficiency, i.e. the received signal from your modem at the cell itself.

4. Originally Posted by JimM
Quite correct JimM, unless you are using one of the Novatels - they need the software to initialise the card. But even with them, you must be disconnected before going through the AT+CSQ sequence mentioned before.

5. Remember to use a 3G or gprs ONLY profile so you can keep the card on the signal you're trying to test.

No good trying to get 3G results and the prefered profile drops you to GPRS...

6. Would there be any interest in me updating the 3G Dialer I wrote last year? It had a basic signal strength graph over time: ftp://ftp.biometrics.co.za/Miscellan...rScreen1.3.JPG

(Bright green at the top is best, black in the middle average and bright red at the bottom is bad ...)

7. Yes,There would be.Ive used your older version many times and would definitly use a new version for the hsdapa cards/..

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