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#41
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John Smith wrote:
... Regards, JS And, I should have included, beg one, buy one, borrow one, steal one, etc. ... Regards, JS |
#42
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![]() "John Smith" wrote in message ... dgleeson422111 wrote: ... Best regards, and thanks for any input. Denis _____________________ http://www.CentronSolutions.com Since most of the posts, in their "EXPERT OPINIONS", relate to your receiver being "de-sensed", do you have a way of negating/affirming this? Desense is definately a possibility, but I still believe that it's at least AS good a chance that it's a standing wave issue on the office end. Others have said to take the 'office' radio outdoors and test the setup that way. That's a good (and simple) test. |
#43
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Brenda Ann wrote:
Desense is definately a possibility, but I still believe that it's at least AS good a chance that it's a standing wave issue on the office end. Others have said to take the 'office' radio outdoors and test the setup that way. That's a good (and simple) test. I'm /still/ more inclined towards a desense problem - cities are astonishingly noisy these days throughout the RF spectrum. I've recently had 4.9 GHz data transmission problems that were eventually traced to a harmonic of a nearby surveillance TV transmitter! Bob |
#44
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On Wed, 29 Oct 2008 14:46:49 +0900, "Brenda Ann"
wrote: "John Smith" wrote in message ... Since most of the posts, in their "EXPERT OPINIONS", relate to your receiver being "de-sensed", do you have a way of negating/affirming this? Desense caused by out of band signals if of course possible when we talk about such toy receivers as most wireless LAN or wireless headphones are. However, since the 868 MHz band is a non-licenced band, it is quite likely that there might be other transmitters (e.g. wireless headphones) in the area of the moving transmitter, but not near the office transmitter. Give a spectrum analyzer to the moving station operator to monitor the interference level in that frequency band, when the moving transmitter is off. A scanner receiver with a decent signal strength indicator might even suffice. Desense is definately a possibility, but I still believe that it's at least AS good a chance that it's a standing wave issue on the office end. This is out of the question for any single frequency half duplex connection, since the path would be reciprocal. In a full duplex dual frequency point to point system between two _fixed_ station, this would be definitively possible. Even in this case, moving the other station by 10-30 cm, you would find a spot, in which there is a good connections both ways. Based on my experience at 1297 MHz with a narrow band (16 kHz) signal in urban environment, you definitively have a lot of multipath nulls (several nulls every meter), For speech communication, this is not much of an issue, the faster you move, you have hundreds of nulls every second and it does not much affect the readability of the speech. The only problem is that if you stop at a traffic light, you usually will end up in a multipath null and the communication is broken, unless you can slide the car a few centimeters. Others have said to take the 'office' radio outdoors and test the setup that way. That's a good (and simple) test. The OP did swap the radios, but he did not tell if the power supply was also swapped. If the office power supply was faulty and the office transmitter could not deliver the nominal power, this could explain the situation. Paul |
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