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DigiSender / XSender DG180 - On Test!

Discussion in 'General Tech & Gadget Forums' started by evochris, Sep 1, 2005.

  1. evochris

    evochris
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    Hi all,

    I haven't been on this forum for a while basically because I didn't need to. My plasma screen set up in the front room is all up and running with out any problems so all is well. However....

    I needed to send the A/V signal from my sky+ box downstairs up to the bedroom. In the bedroom I have a Windows Media Center pc running a 20" TFT screen and an AV amp (well we can't just use a 14" portable can we?!!). Anyway I decided to go with a Digisender from AEI. I connected it all up and found the picture quality to be very good (once I'd removed the wireless network card from the pc anyway!). The problems start when we look at the sound...

    As I had connected the unit to an AV amp and a decent set of speakers I obviously had a good idea of the frequency response of the video sender. The unit is advertised as having HiFi quality sound. Now to me that means a frequency response somewhere in the region of 30Hz - 20KHz. Ok, maybe I didn't expect it to be quite as good as that but atleast somewhere near. Anyway to cut a long story short, the audio quality was far from HiFi sound! It was really lacking bass and the high end treble didn't sound too good either. It also seemed to be slightly distorted at times.

    Anyway, being an electronics engineer and having all the test equipment at hand to actually test the audio response of the units, I did a quick test. Basically this test inputs a constant amplitude sinewave into the transmitter's audio connections. The output of the receiver is measured over a range of different input frequencies. Now obviously a "perfect" system would output the exact same signal that was present at the input. In the real world using RF technology like this this isn't really to be expected... but how did the audio system perform???...

    Well not very well to be honest. The lower "cutoff" frequency was measured to be about 300Hz and the upper to be around 7KHz. Not very impressive at all! This certainly explains where all the bass has gone!!

    Now obviously this is an XSender DG180 which is supposed to be the later model than the DG200 Digisender (very strange numbering system!). My question is has anyone else had any issues with the Digisender audio quality when used on a "high quality" AV system (rather than just a small tv where the problem may not be noticed)?

    I'm currently looking on ebay to see If I can pick up a DG200 cheap just to perform the same test and get a comparison.

    I will get to the bottom of this!!! :)
     
  2. evochris

    evochris
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    Hi all,

    Well just to follow on from my previous post, I managed to get hold of a DG200 X2 version of the digisender. Now this is actually the older version of the sender (the DG180 being the new single scart version). I wanted to perform the same audio response test on this unit to see whether in fact the older version was better. So I connected the DG200 up to the test rig and started testing....

    Well sure enough the audio response was much better on the 200 compared to the 180. Unfortunately I can't post the results graph here (cos I don't know how to!!) However I'll try and give as much detail about the results as possible....

    As I said previously, the DG180 has a very poor low frequency response cutting off at around 300Hz. This was the thing that really made me look further into this problem because trying to play channels like MTV & VH1 through an AV amp was simply painfull to listen to. Another thing that compounds this is that the 180 has a rather "peaky" response "in band" with frequencies around 2kHz having a +3dB gain peak quickly falling off to a high frequency cutoff of only 7kHz @ -3dB.

    You can imagine that this kind of response results in a very piercing mid-range tone lacking any low end bass or high end treble.

    Anyway moving on to the "older" DG200... This system actually has less overall gain than the 180. This may sound bad but believe me it isn't!! Although the peak gain of the 200 is only -1.5dB at 250Hz, the overall response of the system is much flatter with much better bass response. The figures are around 70Hz low cutoff and 9kHz high cutoff. Although having said that, as the DG200 "falls off" at a much flatter rate than the 180 you can get a fairly respectable response from 50Hz right up to around 15kHz.

    So in conclusion It would seem that the DG180 is pretty useless at transporting audio content and reasonable bandwidth. If it's good quality sound you want go for the DG200. Having said that if you are just going to be using the system on a small TV in the bedroom then I'm sure you won't even notice the difference.

    I must just point out that I have only tested the one DG180 system so I can't rule out a fault with this one unit. That's why it would be good to hear from you guys to see if you have found similar problems with the DG180.

    Any questions about all this techno babble above just let me know!!.. Enjoy!

    Chris.
     
  3. p_a_walker

    p_a_walker
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    Hi Chris,

    I have a similar set-up to your good self and am therefore hoping you can help me.

    Downstairs I have Sky+ hooked up to a Philips digisender. This then wirelessly links to a TV in one room upstairs and to a windows vista PC running windows media center in another room upstairs.

    My problem is that I can't get windows media center configured to allow the windows media center remote control to control sky through the wireless connection. When running the variety of tests in windows media center configuration none of the options seem to work (testing while changing channel etc)

    Did you face any such problems?

    Many thanks,
    Paul.
     
  4. scribbler101

    scribbler101
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    Is this the only place here for talk of Wireless Video Senders?

    Basically I want to know if my new toy should be able to drive my Bush DVT-B remotely throught its eye?

    Steve
     

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