---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Fri 03/31/17: 12 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:19 AM - Re: Minimum GPS Antenna Cable Length (Robert L. Nuckolls, III) 2. 07:44 AM - Re: Minimum GPS Antenna Cable Length (Kelly McMullen) 3. 07:55 AM - Re: Minimum GPS Antenna Cable Length (Tim Olson) 4. 08:01 AM - Re: Minimum GPS Antenna Cable Length (don van santen) 5. 08:06 AM - Re: Minimum GPS Antenna Cable Length (don van santen) 6. 08:30 AM - Re: Minimum GPS Antenna Cable Length (user9253) 7. 08:36 AM - Re: Minimum GPS Antenna Cable Length (Stein Bruch) 8. 09:00 AM - Re: Minimum GPS Antenna Cable Length (user9253) 9. 09:41 AM - Re: Re: Minimum GPS Antenna Cable Length (Charlie England) 10. 02:15 PM - Re: Minimum GPS Antenna Cable Length (user9253) 11. 06:34 PM - Thermocouple Wires (William Hunter) 12. 06:56 PM - Re: Thermocouple Wires (user9253) ________________________________ Message 1 _____________________________________ Time: 07:19:52 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Minimum GPS Antenna Cable Length At 06:01 AM 3/30/2017, you wrote: > >I am installing an Appareo Stratus ESG transponder with internal >GPS. It did not come with antenna cables. I purchased a 19 inch >RG400 GPS antenna cable before reading the installation directions >which state, "All wiring should have a cable loss of minimum 2 dB . >. . .Using RG400 the minimum cable length is 10 feet". > Will the GPS work satisfactorily with the short cable? If not, > what is a cheap and easy way to increase the dB loss? What is the > theory behind the requirement for at least 2 dB cable loss? I'm having trouble wrapping my head around this requirement. GPS satellite signals are exceedingly tiny . . . down in the atmospheric noise levels. The only reason our tiny wrist-watch, hand-held, and self-navigating drones work so well is because the 'smarts' in GPS receiver software is looking for specific patterns of data in the chaotic patternless noise. Routine variations in received GPS signals is all over the magnitude map spanning perhaps tens of db . . . a required 2 db 'addition of attenuation' simply doesn't make sense. The idea that a receiver's performance is predicated on a minimum of 2db of loss in the antenna system by making the cable longer is a real puzzle . . . usually, the instructions will say something like "limit cable losses to a MAXIMUM of 2db where a 10' run of RG-400 is the practical limit". I'm wondering if this manual wasn't originally crafted in Chinese and then translated by some academic instead of a systems engineer. One thing is for sure, if you install your system using only the needed length of coax, you can certainly ADD some later. I'm betting a dollar to a dozen doughnuts that it will not be necessary. Bob . . . ________________________________ Message 2 _____________________________________ Time: 07:44:20 AM PST US Subject: Re: AeroElectric-List: Minimum GPS Antenna Cable Length From: Kelly McMullen Garmin came out with the same requirement when the GNS-430W was approved. I believe they later reduced the minimum length to perhaps 6 ft. I suspect it has more to do with matching the output of the antenna pre-amplifier to the main receiver, and doesn't have a lot to do with signal strength at all. On 3/31/2017 7:16 AM, Robert L. Nuckolls, III wrote: > At 06:01 AM 3/30/2017, you wrote: >> >> I am installing an Appareo Stratus ESG transponder with internal GPS. >> It did not come with antenna cables. I purchased a 19 inch RG400 GPS >> antenna cable before reading the installation directions which state, >> "All wiring should have a cable loss of minimum 2 dB . . . .Using >> RG400 the minimum cable length is 10 feet". >> Will the GPS work satisfactorily with the short cable? If not, what >> is a cheap and easy way to increase the dB loss? What is the theory >> behind the requirement for at least 2 dB cable loss? > > I'm having trouble wrapping my head around this > requirement. GPS satellite signals are exceedingly > tiny . . . down in the atmospheric noise levels. > The only reason our tiny wrist-watch, hand-held, > and self-navigating drones work so well is because > the 'smarts' in GPS receiver software is looking for > specific patterns of data in the chaotic patternless > noise. > > Routine variations in received GPS signals > is all over the magnitude map spanning perhaps > tens of db . . . a required 2 db 'addition of > attenuation' simply doesn't make sense. > > The idea that a receiver's performance is > predicated on a minimum of 2db of loss in the > antenna system by making the cable longer is a > real puzzle . . . usually, the instructions will > say something like "limit cable losses to a MAXIMUM > of 2db where a 10' run of RG-400 is the practical > limit". > > I'm wondering if this manual wasn't originally crafted > in Chinese and then translated by some academic instead > of a systems engineer. > > One thing is for sure, if you install your system > using only the needed length of coax, you can certainly > ADD some later. I'm betting a dollar to a dozen doughnuts > that it will not be necessary. > > > Bob . . . > ________________________________ Message 3 _____________________________________ Time: 07:55:51 AM PST US From: Tim Olson Subject: Re: AeroElectric-List: Minimum GPS Antenna Cable Length This is not that unusual. My Garman GNS480 had the same requirement. Keep in mind that the antennas used are active antennas. Tim > On Mar 31, 2017, at 9:16 AM, Robert L. Nuckolls, III wrote: > > At 06:01 AM 3/30/2017, you wrote: >> >> I am installing an Appareo Stratus ESG transponder with internal GPS. It did not come with antenna cables. I purchased a 19 inch RG400 GPS antenna c able before reading the installation directions which state, "All wiring sho uld have a cable loss of minimum 2 dB . . . .Using RG400 the minimum cable l ength is 10 feet". >> Will the GPS work satisfactorily with the short cable? If not, what is a cheap and easy way to increase the dB loss? What is the theory behind th e requirement for at least 2 dB cable loss? > > I'm having trouble wrapping my head around this > requirement. GPS satellite signals are exceedingly > tiny . . . down in the atmospheric noise levels. > The only reason our tiny wrist-watch, hand-held, > and self-navigating drones work so well is because > the 'smarts' in GPS receiver software is looking for > specific patterns of data in the chaotic patternless > noise. > > Routine variations in received GPS signals > is all over the magnitude map spanning perhaps > tens of db . . . a required 2 db 'addition of > attenuation' simply doesn't make sense. > > The idea that a receiver's performance is > predicated on a minimum of 2db of loss in the > antenna system by making the cable longer is a > real puzzle . . . usually, the instructions will > say something like "limit cable losses to a MAXIMUM > of 2db where a 10' run of RG-400 is the practical > limit". > > I'm wondering if this manual wasn't originally crafted > in Chinese and then translated by some academic instead > of a systems engineer. > > One thing is for sure, if you install your system > using only the needed length of coax, you can certainly > ADD some later. I'm betting a dollar to a dozen doughnuts > that it will not be necessary. > > > Bob . . . ________________________________ Message 4 _____________________________________ Time: 08:01:22 AM PST US From: don van santen Subject: Re: AeroElectric-List: Minimum GPS Antenna Cable Length Bob, The first Garmin 430 install manuals stated nothing about the GPS antenna cable length. When the WAAS update was released Garmin stated that the GPS antenna had to be at least 13 feet long. It also stated that it was alright to "coil" the antenna. I know of two RV 10s with G 430s, o e with the 13 foot antenna cable and one with a 3 foot (roughly) anrenna cable. There is no detectable difference in performance. I have not checked the current G430 WAAS manual for cable length requirements. Don On Mar 31, 2017 7:26 AM, "Robert L. Nuckolls, III" < nuckolls.bob@aeroelectric.com> wrote: > At 06:01 AM 3/30/2017, you wrote: > > > I am installing an Appareo Stratus ESG transponder with internal GPS. It > did not come with antenna cables. I purchased a 19 inch RG400 GPS antenna > cable before reading the installation directions which state, "All wiring > should have a cable loss of minimum 2 dB . . . .Using RG400 the minimum > cable length is 10 feet". > Will the GPS work satisfactorily with the short cable? If not, what is > a cheap and easy way to increase the dB loss? What is the theory behind > the requirement for at least 2 dB cable loss? > > > I'm having trouble wrapping my head around this > requirement. GPS satellite signals are exceedingly > tiny . . . down in the atmospheric noise levels. > The only reason our tiny wrist-watch, hand-held, > and self-navigating drones work so well is because > the 'smarts' in GPS receiver software is looking for > specific patterns of data in the chaotic patternless > noise. > > Routine variations in received GPS signals > is all over the magnitude map spanning perhaps > tens of db . . . a required 2 db 'addition of > attenuation' simply doesn't make sense. > > The idea that a receiver's performance is > predicated on a minimum of 2db of loss in the > antenna system by making the cable longer is a > real puzzle . . . usually, the instructions will > say something like "limit cable losses to a MAXIMUM > of 2db where a 10' run of RG-400 is the practical > limit". > > I'm wondering if this manual wasn't originally crafted > in Chinese and then translated by some academic instead > of a systems engineer. > > One thing is for sure, if you install your system > using only the needed length of coax, you can certainly > ADD some later. I'm betting a dollar to a dozen doughnuts > that it will not be necessary. > > > Bob . . . > ________________________________ Message 5 _____________________________________ Time: 08:06:41 AM PST US From: don van santen Subject: Re: AeroElectric-List: Minimum GPS Antenna Cable Length My UPSAT 480 manual did mot list a cable length requirement. I used a 3 foot rg 400 csble and never had any issues with reception. On Mar 31, 2017 08:00, "Tim Olson" wrote: > This is not that unusual. My Garman GNS480 had the same requirement. > Keep in mind that the antennas used are active antennas. > Tim > > On Mar 31, 2017, at 9:16 AM, Robert L. Nuckolls, III < > nuckolls.bob@aeroelectric.com> wrote: > > At 06:01 AM 3/30/2017, you wrote: > > > I am installing an Appareo Stratus ESG transponder with internal GPS. It > did not come with antenna cables. I purchased a 19 inch RG400 GPS antenna > cable before reading the installation directions which state, "All wiring > should have a cable loss of minimum 2 dB . . . .Using RG400 the minimum > cable length is 10 feet". > Will the GPS work satisfactorily with the short cable? If not, what is > a cheap and easy way to increase the dB loss? What is the theory behind > the requirement for at least 2 dB cable loss? > > > I'm having trouble wrapping my head around this > requirement. GPS satellite signals are exceedingly > tiny . . . down in the atmospheric noise levels. > The only reason our tiny wrist-watch, hand-held, > and self-navigating drones work so well is because > the 'smarts' in GPS receiver software is looking for > specific patterns of data in the chaotic patternless > noise. > > Routine variations in received GPS signals > is all over the magnitude map spanning perhaps > tens of db . . . a required 2 db 'addition of > attenuation' simply doesn't make sense. > > The idea that a receiver's performance is > predicated on a minimum of 2db of loss in the > antenna system by making the cable longer is a > real puzzle . . . usually, the instructions will > say something like "limit cable losses to a MAXIMUM > of 2db where a 10' run of RG-400 is the practical > limit". > > I'm wondering if this manual wasn't originally crafted > in Chinese and then translated by some academic instead > of a systems engineer. > > One thing is for sure, if you install your system > using only the needed length of coax, you can certainly > ADD some later. I'm betting a dollar to a dozen doughnuts > that it will not be necessary. > > > Bob . . . > > ________________________________ Message 6 _____________________________________ Time: 08:30:11 AM PST US Subject: AeroElectric-List: Re: Minimum GPS Antenna Cable Length From: "user9253" It seems that the minimum cable length is a requirement of the GPS receiver and not of the antenna. I agree with you Bob. I always thought that shorter cable length is better. I ordered 2 of 90 degree TNC adapters to increase the dB loss. eBay item number: 232142074744 Below is a quote from a separate unrelated company. Notice that they contradict themselves in the last sentence. http://utahscientific.com/support/protected/fb_contemp/GPS%20Installation%20V1_6.pdf > In the world of GPS; too much signal gain can be just as detrimental as too little, and RF noise, even if it is out of band, can severely disrupt the performance of your GPS application. > The Courtyard GPS receiver has a minimum input gain of 20dB and a maximum of 30dB. > The recommended antenna has a 26dB gain. > Recommended cable is RG58 and TNC connectors having a loss of 0.85dB per metre. > (RG174 has a loss of 1.2dB per meter.) > Maximum cable length is: (26dB-20dB)/0.85dBpermetre = 7.06 metres > Minimum cable length is: (30dB -26dB)/0.85dBpermetre = 4.70 meters > As a general rule, keep RF cable lengths as short as possible and use a good quality GPS antenna with the correct gain. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=467869#467869 ________________________________ Message 7 _____________________________________ Time: 08:36:23 AM PST US From: "Stein Bruch" Subject: RE: AeroElectric-List: Minimum GPS Antenna Cable Length That is a fairly accurate statement correct. For others who have 'used' or 'seen' shorter cables work, indeed sometimes they do...but I lost count of the number of phone calls we've had from customers about antenna or GPS issues, only to find out they had a short little cable. Once extending the cable to the proper length most issues disappeared. Our recommendation is to keep it on the longer side - sometimes shorter than 10' will be ok, but something as short as 18" will almost certainly cause issues. Cheers, Stein -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Kelly McMullen Sent: Friday, March 31, 2017 9:38 AM Subject: Re: AeroElectric-List: Minimum GPS Antenna Cable Length --> Garmin came out with the same requirement when the GNS-430W was approved. I believe they later reduced the minimum length to perhaps 6 ft. I suspect it has more to do with matching the output of the antenna pre-amplifier to the main receiver, and doesn't have a lot to do with signal strength at all. On 3/31/2017 7:16 AM, Robert L. Nuckolls, III wrote: > At 06:01 AM 3/30/2017, you wrote: >> --> >> >> I am installing an Appareo Stratus ESG transponder with internal GPS. >> It did not come with antenna cables. I purchased a 19 inch RG400 GPS >> antenna cable before reading the installation directions which state, >> "All wiring should have a cable loss of minimum 2 dB . . . .Using >> RG400 the minimum cable length is 10 feet". >> Will the GPS work satisfactorily with the short cable? If not, >> what is a cheap and easy way to increase the dB loss? What is the >> theory behind the requirement for at least 2 dB cable loss? > > I'm having trouble wrapping my head around this > requirement. GPS satellite signals are exceedingly > tiny . . . down in the atmospheric noise levels. > The only reason our tiny wrist-watch, hand-held, > and self-navigating drones work so well is because > the 'smarts' in GPS receiver software is looking for > specific patterns of data in the chaotic patternless > noise. > > Routine variations in received GPS signals > is all over the magnitude map spanning perhaps > tens of db . . . a required 2 db 'addition of > attenuation' simply doesn't make sense. > > The idea that a receiver's performance is > predicated on a minimum of 2db of loss in the > antenna system by making the cable longer is a > real puzzle . . . usually, the instructions will > say something like "limit cable losses to a MAXIMUM > of 2db where a 10' run of RG-400 is the practical > limit". > > I'm wondering if this manual wasn't originally crafted > in Chinese and then translated by some academic instead > of a systems engineer. > > One thing is for sure, if you install your system > using only the needed length of coax, you can certainly > ADD some later. I'm betting a dollar to a dozen doughnuts > that it will not be necessary. > > > Bob . . . > ________________________________ Message 8 _____________________________________ Time: 09:00:42 AM PST US Subject: AeroElectric-List: Re: Minimum GPS Antenna Cable Length From: "user9253" Below is a quote from Garmin: http://www.vansairforce.com/community/showpost.php?p=824265&postcount=3 > Once the antenna mounting position has been prepared, route the coax cable from the antenna to the 400W Series unit. Proper selection of coax cable and assembly of connectors is critical to GPS signal performance. The cable loss from the GPS antenna shall be between 1.5 dB and 6.5 dB in order to aintain proper rejection to interference signals. > The coaxial connectors and adapters, such as TNC to BNC, add additional loss to the cable and should be considered when computing the cable loss. A typical loss of 0.2 dB can be used for each connection. > NOTE: If RG-142B or RG-400 is used, 1.5 dB equates to a length of approximately 6.5 feet of cable with a connector on each end. RG-142B or RG-400 cable can be used as long as the length is less than 35 feet. Another website says, "Be kind to the 0.000 000 000 000 000 1 watt GPS signal at the Antenna !!" -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=467874#467874 ________________________________ Message 9 _____________________________________ Time: 09:41:51 AM PST US Subject: Re: AeroElectric-List: Re: Minimum GPS Antenna Cable Length From: Charlie England I think we may be losing sight of what signal we're actually talking about. It's extremely unlikely that the GPS antenna puck is sending raw, unamplified 1/5 GHZ RF to the receiver. Most GPS pucks send either decoded digital data (serial or USB), or amplified 1.5GHZ RF, or amplified and downconverted IF (intermediate frequency) to the receiver. If it's either of the 2nd two options, then the next stage (in the receiver) can be overdriven by a very strong signal from the puck. On 3/31/2017 10:57 AM, user9253 wrote: > > Below is a quote from Garmin: > http://www.vansairforce.com/community/showpost.php?p=824265&postcount=3 > >> Once the antenna mounting position has been prepared, route the coax cable from the antenna to the 400W Series unit. Proper selection of coax cable and assembly of connectors is critical to GPS signal performance. The cable loss from the GPS antenna shall be between 1.5 dB and 6.5 dB in order to aintain proper rejection to interference signals. >> The coaxial connectors and adapters, such as TNC to BNC, add additional loss to the cable and should be considered when computing the cable loss. A typical loss of 0.2 dB can be used for each connection. >> NOTE: If RG-142B or RG-400 is used, 1.5 dB equates to a length of approximately 6.5 feet of cable with a connector on each end. RG-142B or RG-400 cable can be used as long as the length is less than 35 feet. > Another website says, "Be kind to the 0.000 000 000 000 000 1 watt GPS signal at the Antenna !!" > > -------- > Joe Gores > ________________________________ Message 10 ____________________________________ Time: 02:15:52 PM PST US Subject: AeroElectric-List: Re: Minimum GPS Antenna Cable Length From: "user9253" I will follow Stein's (and the Mfg's) recommendation and will use a 10 foot cable. They are the experts. It will be a lot easier to do it right the first time. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=467885#467885 ________________________________ Message 11 ____________________________________ Time: 06:34:28 PM PST US From: William Hunter Subject: AeroElectric-List: Thermocouple Wires Hi all , Are thermocouple units polarized? In other words does it matter when connecting up a thermocouple to a dynon EMS unit what wire goes in what pin? THANKS!!! ________________________________ Message 12 ____________________________________ Time: 06:56:46 PM PST US Subject: AeroElectric-List: Re: Thermocouple Wires From: "user9253" >From the SkyView Installation Manual: > Polarity is important, so > ensure that you are routing the positive side (yellow for K-type; white for J-type) of the thermocouple to pin 27 or pin 36 on the 37-pin harness, and the negative side to pin 28 or pin 37 Note that the red wire from type J thermocouples is NOT positive, but is negative. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=467898#467898 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.