A Question Regarding Reception and Data Speeds

The question antenna has received a transmission:
[quote]Morning I have a 597e Air card, which I use as my only means of connection as I am not on a landline, here. I see it has a socket for a extension aerial, Orb has no knowledge of any device can you advise me please? Looking at the data on the dropdown its running at 115.2 Kbps Just wondering if I can get better reception somehow? Thanks a lot..[/quote]
This question has so many components to it, I barely know where to start, but let’s take a crack at it.

First: the 597e. Here’s a handy datasheet [pdf link] that tells us all about the Sierra Wireless 597e. Excitingly, it’s capable of 3.1Mbps download speeds. The sad thing is that this is entirely dependent on the network. Telecom’s CDMA (not XT) network in this case. Before you go grabbing an antenna, there are a bunch of things to consider:

  • Are there heaps of other cellular data users in your area? Cell networks have much higher contention rates than regular landlines. Even a handful of users downloading data from the same cell site will slow data speeds noticably for all users of that cell.
  • How far away is your nearest cell site? An antenna may help, but if you’re too far away, it’s not going to help much.
  • Does your local cell site even support EV-DO Rev A? Or is it still using an older, slower data standard? The only way to find out would be to ask Telecom.
  • Is your computer fooling you? Sometimes a modem will report a speed of 115.2 Kbps by default, when the actual modem speed is much higher. Try a site like SpeedTest.net to see what sort of real-world download speeds you are getting.

Now on to antennas, or aerials. A quick Google tells me that the 597e comes with an SMB antenna socket. I’m pretty sure that’s a standard socket for most car kits, so it might be worth asking about a “car kit antenna”, or find an expert and ask for a cell phone antenna with an SMB plug. If local suppliers can’t help you out, you could always import an aerial and connector from an international retailer like these guys or those ones.

If you’re extremely keen on something cheap and cheerful, remember that an antenna is nothing more than an exposed piece of wire. If you use an antenna calculator, you can see that even the full-wavelength size of a 1900MHz antenna is only about 6 inches. You could grab an SMB plug, connect it to some coaxial cable, then strip the last 6 inches off the cable to expose the conductor. Voila! An antenna! Of course the pro antennas come with base loads and boosters and all sorts of good stuff which makes them better than bare wire, but it might be worth a crack for a really cheap boost.

Good luck!

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1 Comment

  1. If you look at the Sierra connection monitor software (the thing that looks like a fake LCD control panel), how many bars of signal strength does it show?

    Does it indicate that you have a 1X connection? It will say '1X' on the panel.

    If you only have a couple of bars signal strength, then you could benefit from an external aerial.

    The telecom shops here used to sell a small plastic omnidirectional aerial you could clip on to a laptop, looked like a plastic spatula about 150mm long.

    Other than that, I guy I know who uses a USB T3G modem has a directional Yagi aerial that he reckons gives him 2Mb about 10km from the Hunua tower.

    If you are in NZ,check out cellutronics anyway, I know they can give you advice on the Sierra cards


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