434mhz-900-1200mhz-2,4 or 5,8ghz: the best?
Posted 21 January 2008 - 09:36 AM
I have tested a 2,4ghz with 700mw and 2 patch antennas with 24db each,with oracle diversity,quality is good,but i need a stable video in all condition,i think wich 434mhz can be a solution,but i need your suggest,because i can't find uhf video transmitters in my country.
Posted 21 January 2008 - 10:15 AM
Very good quality video can be achieved with the popular A/V systems. It is all a matter of using a well proven A/V Tx and Rx, choosing the antenna system that is best for your application, and giving close attention to the installation. With microwave RF, everything matters.
It would be good to post examples of the video you are experiencing now. That way others can offer advice on whether or not you are achieving the results we expect from a typical A/V system. It is also wise to list all the equipment you have, including their model numbers.
Posted 23 January 2008 - 11:25 AM
and then we can support you much faster, you can even be lucky to meet new pals in your area
Posted 13 March 2008 - 04:04 PM
Posted 19 March 2008 - 05:39 PM
Posted 20 March 2008 - 12:52 PM
Posted 28 March 2008 - 04:52 AM
I seem to remember somebody saying lower frequencies work better around obstacles. And it would seem like 900mhz would be a better choice for flying with a 2.4ghz radio. One of the downfalls to 900mhz would be the size of the patch antenna. It would be HUGE compared to a 2.4 antenna! Hmm....I'm thinking 900mhz is my best choice, especially since there aren't cell networks and other systems operating on that frequency.
The patch antenna at 900Mhz isn't that big. It's about 10 inch square I suppose, from memory.
Yes you are right about the fact that 900 is better around obstacles. I would always go 900Mhz over 2.4G because of the amount of other stuff using 2.4Ghz, like wireless Lans, bluetooth, R/C transmitters now etc. 2.4Ghz will also suffer from reflections and a much higher path attenuation than 900MHz. The signal path attenuation gets lower with frequency, but as RC Cam already said, so does bandwidth. But 900 is a good compromise. I've got 900MHz gear and am very pleased with it's performance, especially when using an 8dbi path antenna. I would say the rx antenna is more important than the output power of the tx too.
Posted 28 March 2008 - 10:20 AM
Posted 31 March 2008 - 08:27 PM
That all changed when I added 2 high gain patch antennas to the Diversity RX on the 2.4 Mhz. Wow, very clear and range is great. We only test fly at 500 ft and below, and within a 1 KM radius of the antenna but I was impressed. I played with the patch orientation and it matters immensely. Low to the ground seems to work best. I am purchasing the ultimate diversity package with 2 yellow jackets and the oracle. I am eager to test that setup! I did notice a slight line or 2 across the screen when crossing over antenna, but they were pointed in such a way as to have a big section of low gain between them.
I have also ordered a 900 Mhz patch antenna.
Low frequency radio waves travel further and penetrate objects better. So higher the frequency the more signal bounce you get. I tested the 900 MHz system in my apartment and I could walk to my on suite bathroom, place the 900 Mhz RX inside the bath and still receive a great image. (3 brick walls and 50 Meters away ). The bath is steel so it is my favorite signal suppressor. Also the walls between rooms are very thick.
The 2.4 Mhz showed cutouts after walking into the bedroom...I noticed that my wireless mouse, wireless LAN make the 2.4 Mhz RX chirp and can cause interference to the video signal. The 900 Mhz does not get this but instead if the TX is placed too close to some servos on my heli they move around. The futaba S9451 servos seem to be ok. The JRs are terrible. The Futaba S9255 are susceptable to the 900 Mhz interference. Incidentely smaller analogue servos seem more resiliant against RFI. The 2.4 Mhz does not have any effect on any of the servos.
I guess this means placement on the airframe is a bit more critical with the 900 Mhz system.
Posted 01 April 2008 - 03:02 PM
Posted 03 April 2008 - 01:08 PM
I'm thinking of upgrading from my current 1.2 system to a new system from Rangevideo, but can't decide which frequency to go with. I just fly a couple hundred feet high and cruise around usually, with a slow stick and an Easystar, but I really would like to fly around the trees at relatively low altitude. Which frequency should I go with, and why?
Phil: I have both the 900 MHZ with 500 milliwatts of RF power from Range Video or 2.4 GHZ with 1000 milliwatts of power.
My choice is 900 MHZ. The reason? because you can have it with either 2.4 GHZ such as the Spectrum 2.4 Radio or USA the 72 MHZ aircraft use radio. Also no conflicts. Here is a High altitude video from Hawaii. Remember you tube video is substandard compared to original video I have recorded. Archos 605 I used to record.
Also Here another field:
I have another while the sun was in the west. What a beautiful view of second field at a later soon to post. Kawainui Airstrip
Note: That day I was outside the tca so ok to fly high.
Posted 03 April 2008 - 02:26 PM
Posted 03 April 2008 - 03:42 PM
As an aside, how about some pix of Hotel St. Spent many happy hours there in 61, 62 & 63.
Edited by W3FJW-Ron, 03 April 2008 - 03:44 PM.
Posted 03 April 2008 - 04:10 PM