<div class="gmail_quote">On 9 June 2010 16:50, Thomason, Simon <span dir="ltr"><<a href="mailto:Simon.Thomason@racq.com.au">Simon.Thomason@racq.com.au</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
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<p class="MsoNormal">Was wondering if anyone has had a bit of experience with testing of signal strength of different carriers’ wireless 3G devices/services. Weather this be a piece of software or hardware that can provide a little more information that the
standard fair from a USB dongle</p>
<p class="MsoNormal">Ideally I am interested in a piece of software that resides on a remote machine that can report back to a head end that can keep historical information and can be reported on.</p></div></div></blockquote>
<div>I've done a fair amount of this stuff before. IMEI define standard AT-commands you can use to control/query the mobile terminal. The IMEI specs are <b>very</b> good and the Falcom and Nokia devices I've used in the past have very consistent behaviour (i.e. follow the spec well). </div>
<div><br></div><div>In Windows, and depending on the device, it will normally present to you as a number of asynchronous serial devices as COMn: ports. One of these will be the command device that lets you control the mobile terminate via AT commands (refer to the IMEI specs for this - they are really good). I was going to tell you that that is probably no use to you when your vehicles are on the road because that port is probably locked but I just tested it on my lappy and the command port is fine for use when the Sierra stack is connected and working.</div>
<div><br></div><div>Hence:</div><div><div><font class="Apple-style-span" face="'courier new', monospace">at+csq</font></div><div><font class="Apple-style-span" face="'courier new', monospace">+CSQ: 20,99</font></div>
</div><div><br></div><div>The first value is the receive signal strength indicator (RSSI) and the second is the bit error rate. 99 = unsupported on this modem. No matter, you don't need the BER value anyway. There are tables that convert CSQ values to dBm but you probably want to read the manufacturer specs for your MT gear to work out what is available and what special cases/notes there are. I have not looked into the specifics of getting CSQ figures for different bands and so on. There might be a revised set of commands that exposes that stuff.</div>
<div><br></div><div>So in practical terms, and I assume your platform is those in-vehicle windows boxes on the RACQ trucks that bring me batteries, I'd probably suggest that you write an NT/CE service that runs on your fleet vehicles that: </div>
<div><ol><li>Grabs the current RSSI from the MT command device using AT commands.</li><li>Grabs the current lat/lon pairs from your onboard GPS.</li><li>Log the above into a SQLExpress/Compact instance on the vehicles.</li>
<li>Punts that up to a head end web service periodically.</li><li>Presto, you're done.</li></ol>While you're at it and seeing as you're on the road, check unencrypted 802.11abgn traffic on 2.4 and 5GHz, maybe addresses of famous peoples nearby, and any salacious web sites and grab them too for serving ads later. </div>
<div><br></div><div>Also, and more seriously, I would fortify any sort of dBm figures you collect with at least a perfunctory real-world performance/transfer test. After all, the reported signal strength values can be seen as advisory to some degree - but mbps actually copied to your remote terminal - well, that is <b>real</b> and hard to fudge. :) </div>
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<p class="MsoNormal">Also was wondering if anyone could give an idea of there experience with latency over different networks in regards to 3G. A good comparison would be the difference that can be experience from a wired connected to a 3G in the same area
to the same destination.</p></div></div></blockquote><div>No one probably outside of RACQ can give you those A/B figures as it is very difficult to do for a corporate and not entirely fair in some cases. The Internet side of the IP traffic may emerge at different places at different times on the terrestrial network depending on what the mobile operator wants to do. Also, for a corporate like RACQ, you generally get special SIMs with special certs/APNs/etc that terminate the traffic inside your own corporate network via either a VPN or other private link with your own internal addressing and route to the Internet. In that scenario, you have a very special and unique scenario for egress from the wireless network that no one outside your company can really comment on or help you with in terms of generating a like-for-like comparison. Sorry.</div>
<div><br></div><div>Unscientifically however, and IMO, there is only one game in town for wireless and that is NextG. I persisted with a 3 dongle for some time but any time I went even remotely out of town there was nothing but GPR$ to fall back to. That might have improved recently - but I doubt it. My informal testing on other people's iPhones on Voda and Optus has been pitiful by comparison. </div>
<div><br></div><div>Also, the <i>type</i> of 3G connection has a big impact on latency. HSDPA vs HSUPA etc. </div><div><br></div><div>I hope that helps. <br><br></div><div>David.</div><div><br></div></div>-- <br>David Connors (<a href="mailto:david@codify.com">david@codify.com</a>)<br>
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