Interference Problems?

[Mastermime]

Hey guys,

Would there be any interference problems if I had to transmitters on my robot, but one is transmitting at 900 mhz and the other is transmitting at 2.4 ghz?  I dont think there will be, but I just wanted to make sure.

Thanks

[Soeren]

Hi,

Would there be any interference problems if I had to transmitters on my robot, but one is transmitting at 900 mhz and the other is transmitting at 2.4 ghz?  I dont think there will be, but I just wanted to make sure.

Hard to say, as it depends on...
Distance between antennas.
Shielding on the respective transmitters.
Modulation.
Even the orientation of coils within each of them, but shielding and reorientation can handle such issues.
Selectivity
This is assuming they're transmitting concurrently, if that can never happen, you just have to be careful with antenna positioning.

But why? using either/or would be more sensible.


Please use the correct terms. There's no such thing as mhz it's MHz, M for Mega (=1,000,000 while "m" means milli = 1/1000 or 0.001 an Hz is named from the scientist Hertz, so should be capitalized. Same goes for "ghz", which should be written as GHz.

[Mastermime]

Hard to say, as it depends on...
Distance between antennas.
Shielding on the respective transmitters.
Modulation.
Even the orientation of coils within each of them, but shielding and reorientation can handle such issues.
Selectivity
This is assuming they're transmitting concurrently, if that can never happen, you just have to be careful with antenna positioning.

I'm pretty new to wireless setups so I am not sure what shielding, selectivity, and modulation is (Is this encoded wave signals?)  Could you or someone else give me a brief explanation of what these are.

But why? using either/or would be more sensible.

I am using an Xbee Pro XSC (900 MHz) for the data transmission such as controlling motor speeds, switch things on/off, etc.  I am using a different transmitter to transmit video because the Xbee is not capable of transmitting live video data.

Please use the correct terms. There's no such thing as mhz it's MHz, M for Mega (=1,000,000 while "m" means milli = 1/1000 or 0.001 an Hz is named from the scientist Hertz, so should be capitalized. Same goes for "ghz", which should be written as GHz.

I'm sorry I was typing very quickly and did not realize my mistake.  Thanks,

[Mastermime]

Would there be an issue if I switched my transmitter from 2.4 GHz to 1.2 GHZ?  Will there be interference since its a pretty close frequency?

[Soeren]

Hi,

Would there be an issue if I switched my transmitter from 2.4 GHz to 1.2 GHZ?  Will there be interference since its a pretty close frequency?

I don't know your application, so I cannot give you any hard facts. You have to try it an see and then work out any issues.
Exactly halving the frequency probably won't do much difference, but you really have to test it.

[Mastermime]

Ok I will test it and then bring back my results/ problems.

[Mastermime]

Actually before buying the transmitter and receiver for the video transmission, would you guys mind if you quick checked over this product to make sure it will produce the results I'm looking for (clear transmission of up to 1500 ft).  I am still a novice when it comes to wireless transmission.  I just do not want to return this all the way back to China realizing this is not what I need.

Here is the link to the ebay item

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=120811648140#ht_2065wt_1189

[Soeren]

Actually before buying the transmitter and receiver for the video transmission, would you guys mind if you quick checked over this product to make sure it will produce the results I'm looking for (clear transmission of up to 1500 ft).  I am still a novice when it comes to wireless transmission.  I just do not want to return this all the way back to China realizing this is not what I need.

Here is the link to the ebay item

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=120811648140#ht_2065wt_1189

Well, your guess is as good as mine on whether they tell the truth, but they claim:

Transmission distance without obstacle：～2500m

(~8,200')
Sounds a bit optimistic to me, but they don't specify at what S/N ratio or such, so they can pretty much write anything, just like when selling LED's of so-and-so-many mCd but not telling the angle of half intensity - sort of just half an answer.

OTOH, you won't find any transmitter/receiver set with a guaranteed  minimum range, as this is impossible, which is why they write...

Notice:
For better reception, make sure that the transmitter and the receiver are placing at least 5 feet above ground. Distance affected by the nature of environment such as noise, weather, traffic, building, trees ... etc
Antenna must be attached on the transmitter before power up. Otherwise, the transmitter will be burned out because the excess power cannot be released by the antenna.

So, they've covered their behinds and I wouldn't trust any refunds if it won't work optimally!
They have a measly 31 sales and even sellers with thousands of sales have a tendency to vanish if you want a refund (yeah, we've got the T-shirt too ) and they know you're not going to travel to China or make much legal fuzz about cheap goods.

If you cannot afford to be taken for a ride, go to a high street shop and ask for proof of range (a test should do).

It all boils down to you having to make the decision, as it's your $62,- on stake.

[Mastermime]

Ok he has vanished recently.  I have been asking him questions and he hasn't responded.  It all seems too good to be true.