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Apr 04, 2009, 02:42 AM
Microcontrollers lover !
Serveurperso's Avatar
Discussion

900MHz video receiver sensitivity improvement searching !


Hi

With everything you say about 900MHz vs. 2.4GHz video downlink, I deduced/suppose :

The best system is RangeVideo "900MHz" TX/RX + industrial ultra low noise antenna preamp for RX + tuned antenna to desired channel.
(+ new dpcav RF lowpass filter on TX to protect RC receiver, and industrial DC-DC TRACOPOWER to power supply all onboard video system)

One who seems best suited : http://minicircuits.com/pdfs/ZX60-1215LN+.pdf $150 each : buy, plug SMA gender changer, and play !!!

50Ω, 800 MHz to 1400 MHz
Ultra low noise figure 0.4 typ.
11V-13V operation
Good IP3, 27 dBm typ.

This industrial product + PLL rangevideo RX must significantly exceed all 2.4GHz video receiver sensitivity and Signal-to-Noise ratio !!!!???!!!!

An expert in radio frequency/ATV to confirm/help ?
What the brand of 900MHz rangevideo RX ? (lawmate or not ?) ***EDIT*** Rangevideo TX http://www.racewood.net.cn/enproduct.asp?smtid=1175 and RX http://www.racewood.net.cn/enproduct.asp?smtid=1183 is from RACEWOOD
Does the new dpcav RF lowpass filter can operate in reception (to protect RX preamp from TX, two watts wifi/802.11g LPA for 2.4GHz spektrum uplink) ?

Regards,
Pascal



And : http://www.alltronics.com/cgi-bin/i...mp-900-1000-MHZ other very cheap preamp but no datasheet (Linear ? GaAsFET ? S to N ratio ?)

Or : Standard/cheap satellite broadband inline preamp : noise <5db, good, bad for RX tuner ? Or : Satellite LNB preamp part ? Or : Cheap RAMSEY SA7 broadband http://cgi.ebay.com.sg/Ramsey-SA7-B...Qc mdZViewItem ?
Last edited by Serveurperso; Apr 11, 2009 at 01:57 PM.
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Apr 04, 2009, 09:04 AM
Microcontrollers lover !
Serveurperso's Avatar
ZX60-1215LN-S+ is wideband and need filter for GSM900:s

Pascal
Last edited by Serveurperso; Apr 07, 2009 at 10:05 AM.
Apr 04, 2009, 02:44 PM
fast
fmkit's Avatar
LNA only needed to compensate cable loss,
if antenna connected stright to receiver
there is nothing to compensate so LNA won't do any good

look at video output while no signal, if you see lots of black and white vivid dots (noise) the system has enough gain
if you see sort of gray with tiny dots that may be low gain, try LNA or repair the receiver.
Apr 04, 2009, 06:17 PM
Microcontrollers lover !
Serveurperso's Avatar
Quote:
If you see sort of gray with tiny dots that may be low gain, try LNA or repair the receiver
Yes, gray with tiny tiny tiny dots, on my two receivers. but it's NORMAL, it's a low sensitivity satellite tuner (comtech module ?), noise floor is very low.

The rangevideo 900MHz TX is a very good TX, real 500mW (630mW peak RF power on middle ch 2 and 3 !!!). The receiver is based on a old but very widespread technology....

This RX use a standard analog satellite receiver tuner. It was supposed to work with sattelite LNB. it's a BROADBAND tuner.

This tuner does not have the sensitivity of new NARROWBAND 2.4GHz tuners still in development.

But, if you add very low noise (GaAs FET based) PRE-amplifier with band-pass filter (or good combination of low-pass filter and high-pass filter), you cumulate NARROWBAND advantage (best signal to noise ratio) and all lower & undisturbed frequency (1GHz) advantages.

Pascal
Last edited by Serveurperso; Apr 07, 2009 at 07:33 AM.
Apr 04, 2009, 06:54 PM
JettPilot's Avatar
I use a Preamp for my 900 MHZ equipment from Down East Microwave. I dont detect that much of a difference in range. Maybe it is overloading my reciever ??? I wonder if this minicircuits preamp is better than the one I have. The price is the same, but this one looks a lot smaller. Here is the preamp I use for 900 MHZ video. I should get a bandpass filter, maybe strong out of band signals could be causing problems for my preamp and reciever also...

http://www.downeastmicrowave.com/cat-frame.htm

Minicircuits also sells a very small BANDPASS filter with SMA connectors for the receiver which I am thinking about buying. They are only like 40 bucks each. I suspect I may be seeing reduced video range due to strong out of band transmissions in the area ( Cellular etc. ). Anyone have any thoughts on this ?

Mike

Mike
Apr 05, 2009, 05:42 AM
fast
fmkit's Avatar
look what I did using 900mhz RF can extracted from cordless phone,
tapped into existing LNA and filter, now my video receiver is sharp tuned to single channel while being incredibly sensitive, as good as it gets
note that sweep diagramm is better than shown because I used noon RF connectrors for testing, whwn LNA is in use it has in-out soldered direct w/o connectors


Quote:
Originally Posted by Serveurperso
The rangevideo 900MHz TX is a very good TX, real 500mW (630mW peak RF power on middle ch 2 and 3 !!!). The receiver is based on a old but very widespread technology....

This RX use a standard analog satellite receiver tuner. It was supposed to work with sattelite LNB. it's a BROADBAND tuner.

This tuner does not have the sensitivity of new NARROWBAND 2.4GHz tuners still in development.

But, if you add very low noise (GaAs FET based) PRE-amplifier with band-pass filter (or good combination of low-pass filter and high-pass filter), you cumulate NARROWBAND advantage (best signal to noise ratio) and all lower & undisturbed frequency (1GHz) advantages.

Pascal
Apr 06, 2009, 04:55 AM
Microcontrollers lover !
Serveurperso's Avatar
The hard to find part is the bandpass filter.

For this RangeVideo TX the best channel is the number 3.
Ch 1 910MHz -> GSM900
Ch 2 980 MHz -> Near GSM900
Ch 3 1010 MHz -> perfect, empty, low noise in france (but illegal)
Ch 4 1040 MHz -> Near 1090MHz hi power but very low duty cycle digital noise (airport/aircraft ?).

I need a narrowband filter centered on 1010MHz
1010MHz Antenna -> 1010Mhz bandpass filter -> Any broadband but low noise preamp -> Basic Satellite tuner or Rangevideo receiver.

http://www.gw4kaz.cymru1.net/wq_page_4.htm
http://www.vitsch.net/ham/homebrew/23cm_filter/
http://www.ussc.com/~uarc/utah_atv/interdigital1.html

Pascal
Apr 06, 2009, 06:06 AM
Microcontrollers lover !
Serveurperso's Avatar
I love this filter !!!!!!!! I'm Ready for very high gain low noise preamp Edit : it's too expensive !!!!


http://coaxialfilter.com/itemdesc.as...210001&eq=&Tp=
990 - 1010 MHz Ceramic Filter SMT -> too narrow for composite signal on 1010MHz, need bandwitch over 1010MHz (<1020MHz)

SPECIFICATIONS:

P/N: C0210001
Ceramic Bandpass Filter Surface Mount,
Center Frequency (Fc) = 1000 MHz,
Insertion Loss < 3 dB at Fc,
VSWR < 1.5 : 1 at Fc,
3 dBc Bandwidth = 20 MHz nominal,
Impedance is 50 Ohms nominal,
Rejection > 50 dBc at Fc 100 MHz
Power handling = 1 W,
Operating Temperature = -40 C to +85 C,
Weight = 0.1 Ounce,
Mounting is by reflow soldering tabs at 220 C - 230 C 10 sec max,
Connections are 0.020" dia RF pins silver plated,
Finish is silver plated,
Size is 0.26" H x 0.70" x 0.50" excluding pins and tabs.

Or : http://coaxialfilter.com/itemdesc.as...610001&eq=&Tp= Easy with SMA (plug & play with only one SMA gender changer) !! Perfect for Composite bandwitch on 1010MHz, Perfect to reject GSM900 and 1090MHz airplane digital hi power/short burst, very good insertion loss, can improve Rangevideo/satellite receiver without a preamp Especially in my case I use omnidirectional antennas !!!

SPECIFICATIONS:

P/N: B0610001
5 pole Combline Bandpass Filter,
Center Frequency (Fc) = 1000 MHz,
1 dB Bandwidth = Fc +/- 30 MHz,
Insertion Loss < 1.5 dB at Fc,
VSWR < 1.5 : 1 typ,
Rejection > 60 dB at Fc +/- 150 MHz,
Mounting is by tapped holes in body,
Connectors are SMA female and female,
Finish is white epoxy paint per MIL-PRF-22750F,
Size is .50" H x 1.50" W x 1.50" L excluding connectors.

Now I need THE preamplifier !!!

Pascal
Last edited by Serveurperso; Apr 07, 2009 at 07:36 AM.
Apr 07, 2009, 04:01 AM
Microcontrollers lover !
Serveurperso's Avatar
Hi,

Quote:
Minicircuits also sells a very small BANDPASS filter with SMA connectors for the receiver which I am thinking about buying. They are only like 40 bucks each. I suspect I may be seeing reduced video range due to strong out of band transmissions in the area ( Cellular etc. ). Anyone have any thoughts on this ?
http://minicircuits.com/cgi-bin/mode...1065%2b&tb_no=
Yes, a lot cheaper & Online order !!!!! somes is direct plug & play for antenna/rangevideo RX but poor R/C filter bad GSM900 rejection...

Cheap Not narrowband filter, unusable for antenna filter + preamp

Pascal
Last edited by Serveurperso; Apr 07, 2009 at 07:37 AM.
Apr 07, 2009, 05:40 AM
Registered User
hey Pascal.
please no offence but this is useless tread that may mislead some people
Even if you have access to GHz band spectrum +tracking generator / network analyzer these plug-n-play components won't work as specified cause interconnect itself is a black magic art, you need years of RF experience to design and test 20MHz bandpass LNA
Apr 07, 2009, 06:48 AM
Microcontrollers lover !
Serveurperso's Avatar
FPV_now : No no and no I use industrial pre calibrated hardware : With RF bandpass filter DIRECTLY behind the tuned antenna and DIRECTLY connected to any UHF VERY low noise preamp (commercial 50 Ω <0.5db noise figure) I am sure to IMPROVE ANY satellite analog tuner performance !!! You have to be very fussy about the realization As to achieve a small t-rex 250 FPV helicopter.... "black magic art" lololol Amateur television (legal or not) it's not magic, it's physic !!!
FPV heli T-Rex 250 sunday flight... (8 min 50 sec)


> For you in US, ch1 910MHz is 100% LEGAL and undisturbed by GSM900, you can ****PLUG AND PLAY, NARROWBAND, SMA & 12V ready **** this CHEAP $70 industrial EBAY LNA http://cgi.ebay.com/902-928MHz-ISM-L...3286.m20.l1116 (Frequency Range: 902-928MHz; Noise Figure: 1.2dB at 915MHz Gain: 24dB at 915MHz ) to RANGEVIDEO RX (without filter already inside LNA) and improve ****DRAMATICALLY**** your range. For long range a good receiver with a good antenna is more important than big transmit power.

He is deaf to this use in air reception on one channel. Any 1.2GHz amateur TV use preamp & filter with satellite tuner. (DIY interdigital type) with very good reception improvement !!!

For ATV, some ham use Poor <5db Noise Figure BROADBAND satellite "cable booster / in-line signal amplifier" as antenna pre-amp, and have reception improvement with home made interdigital filter !!!

I found this (for GSM900 reject & legal country ony) , cheap & narrowband !! 1000 MHz Ceramic Bandpass Filter !!! $52 !!!

This $50 ceramic filter have similar performances as 4 poles inter digital filter !

http://www.amcrf.com/Pdf/AM1000B1051.pdf

Center Frequency (F0) 1000 MHz
1 dB Bandwidth(BW) 35MHz typ (good for video on ch 3, 1010MHz rangevideo TX)
Insertion Loss (F0) 3.0 dB max
Ripple in BW 0.7 dB max
VSWR (Fo) 1.5:1
Attenuation 50dB min at 865MHz (20/30db of GSM900 attenuation)
50dB min at 1135MHz
In/Out Impedance 50 Ω

I will order two filters and continue my adventure. Now I need UHF <0.5dB low noise figure preamp with >20dB <40dB gain. Easy to find compared to this filter!

Pascal
Last edited by Serveurperso; Apr 08, 2009 at 04:01 AM.
Apr 07, 2009, 11:47 AM
Registered User
Daemon's Avatar
Quote:
Originally Posted by JettPilot
I suspect I may be seeing reduced video range due to strong out of band transmissions in the area ( Cellular etc. ). Anyone have any thoughts on this ?
External interference has completely pushed me off 900Mhz around
urban areas. 1.3Ghz is cleaner for me. For all I know, it could be in-band
noise as there are other 900Mhz applications out there like longer range
WiFi networks and such. I'm certainly interested in your results with a
band pass filter.

ian
Apr 07, 2009, 02:27 PM
Microcontrollers lover !
Serveurperso's Avatar
Normaly Ch3 1010MHz of 900MHz kit is not affected by GSM900, Even near of GSM relays, I tested. Do you have limited version of the TX with only Ch1 ? Do you have GSM900 digital band in your country ?

A bandpass filter is interesting for broad/wideband LNA.

This cheap ebay broadband LNA work for 1010MHz (ch3) : http://cgi.ebay.fr/ws/eBayISAPI.dll?...m=280325926644

"Q : Yes it will work at 1010mhz and the gain would be about 18 db. Thank you Jeffrey Kitz Technologies"

18db it's not bad... 1 db of noise figure is not bad...
Edit : No SMA... not plug'n'play need tinkering

Pascal
Apr 28, 2009, 04:20 PM
Microcontrollers lover !
Serveurperso's Avatar

My first mod !


Riddle! How to double performance of this ComTech I2C PLL tuner !
Apr 28, 2009, 04:38 PM
fast
fmkit's Avatar
why replace existing IF filter with identical one ?

I've modified bunch of these tuner cans, only mode that is worth to do is replacing pcb strips/varactors with simple 3mm 2turns coils and 1pf capacitors to form fixed channel tuner, this mod gives near 20db gain without adding any active conponents(transistors or MMIC). Those without tracking generator should not attempt tweaking the front-end.


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