# Wireless Systems



## co1615 (Jan 20, 2010)

Hello,

Not sure if this is the right forum but I'm trying to find out about signals between a wireless transmitter and receiver. 
I have customers call saying that they have to hold the transmitter within 1-2 feet of the receiver to get it to work. There should be about 100 foot range. I'm not sure of the frequency, but it's not 433Mhz. The batteries have full power and there is nothing on the machine that would cause interference.

Anyone have a suggestion?

Thanks,
Trent


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## Done_Fishin (Oct 10, 2006)

some of them have two channels(switchable) when we are talking about headphones or mice, networking has up to 14 depending upon the region and if memory serves me correctly they are ALL in the 2.7GHz range.

if they are working on the wrong frequency (Transmit - Recieve) that could upset the system.

ideally they should be transmitting freely in an area where no-one else is alo transmitting on the same frequencies (ie wireless network might interfere with headphone or mouse because it would need to boost power to compensate for loss of signal due to another transmitter transmitting on the same or nearby frequency channel)

Some electrical equipment can cause problems, like motors or microwave ovens, environmental factors could cause problems but not within the same 4 walls unless something else is transmitting on the same frequency.

the only other thing that comes to mind is the aerial .. hopefully it's attached and making contact.


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## co1615 (Jan 20, 2010)

This is on brand new machines, we just started having them assembled in China and are using a different transmitter/receiver combo. We used to use Delta Systems, not sure who makes the new system. The antenna is molded into the receiver.


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## Basementgeek (Feb 7, 2005)

Since this is a business venture I strongly suggest that you contact a certified lab to test them.

BG


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## Done_Fishin (Oct 10, 2006)

They should be using 2.4GHz if it's for networking but I see that there is a band 2.3GHz ~ 2.7GHz which might be for general use. there is also a 3.6GHz and a ~5GHz band

Different areas of the globe have different numbers of channels within the transmit frequency.

see this http://en.wikipedia.org/wiki/List_of_WLAN_channels

What equipment are we talking about ?

do you access to a spectum analyser to 1. see what frequency is being transmitted 2. transmit a signal to see what frequency the reciever responds at .

for an amusing discussion about channel overlap (basic discussion about 3 or 4 channel transmission doesn't appear to apply here but it might help you understand what might be happening on your particular device)

see this page 
http://airheads.arubanetworks.com/a...and-elizabeth-discuss-2-4ghz-channel-planning

edit: 

http://www.mobileisgood.com/wifi.php



> *Disadvantages of Wi-Fi*
> 
> * Spectrum assignments and operational limitations are not consistent worldwide; most of Europe allows for an additional 2 channels beyond those permitted in the US; Japan has one more on top of that - and some countries, like Spain, prohibit use of the lower-numbered channels. Furthermore some countries, such as Italy, used to require a 'general authorization' for any Wi-Fi used outside an operator's own premises, or require something akin to an operator registration. For Europe; consult http://www.ero.dk for an annual report on the additional restrictions each European country imposes.
> 
> ...


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## co1615 (Jan 20, 2010)

This isn't a phone or computer, it's a tow behind road grader. The wireless controls the up and down movement of the teeth to grade the road.


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## Done_Fishin (Oct 10, 2006)

Large metallic objects can create major problems by shielding or deflecting signals. reflected signals can cause cancellation of signal .. how does the equipment behave "on the bench"


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## co1615 (Jan 20, 2010)

Ok, got a little more info. Both transmitters are 433.92 Mhz.


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## Done_Fishin (Oct 10, 2006)

Done_Fishin said:


> Large metallic objects can create major problems by shielding or deflecting signals. reflected signals can cause cancellation of signal .. how does the equipment behave "on the bench"


have you reproduced the problems within your establishment or are you just taking your customers word for it currently ?


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## co1615 (Jan 20, 2010)

We didn't have one of the new receivers to try, the warehouse is 20 miles up the road from where I am. We have had multiple calls though.


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## Done_Fishin (Oct 10, 2006)

Is this your first production run with this equipment? If a new Production run, have their been any similar problems with earlier batches?

how widespread have your "calls' come from? Are they all in the same area or random?

Currently I would say that you require specialist equipment (Spectrum Analyser) that will allow you to check the transmission / reception frequencies and their power output / sensitivity.


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## co1615 (Jan 20, 2010)

It is a new production run. I've got the engineer's involved now.


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## Done_Fishin (Oct 10, 2006)

Without proper equipment and devices to be analysed it is difficult to offer advice.


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## co1615 (Jan 20, 2010)

I appreciate the help. I know the frustration of "lack of information" from customers!


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## Done_Fishin (Oct 10, 2006)

You're welcome. I was involved in Electronics Production - Test Section for many years and I know only too well what could happen when products are manufactured, especially facon.


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