Re: [RCSE] Pager? Interference
On Fri, Oct 22, 2004 at 02:26:11PM -0600, Howard Mark wrote: | Now to my question. Is it possible that this is pager interference? Of course. But there's no way to tell for sure. You said that people were trying to locate the signals with scanners. Do you know what kind of scanners they were using? If you're using one that you can listen to, the data transmissions sent by a pager have a very definite sound. Also, they're not usually on all the time -- instead, they may last only a few seconds, and happen only every few minutes, making them hard to track down. Of course, R/C receivers aren't known for their awesome abilities at rejecting interference. Depending on how they're designed, they're not only vulnerable to interference on and near their designated channel, but may be vulnerable to interference at other totally different frequencies as well. Good design reduces their vulnerabilities to other signals, but it's difficult to remove them all and yet keep your receiver small and cheap. Probably the best way to determine if a specific receiver is getting hit is to get another, identical receiver, with the same crystal, and crack it open and put an amplifier in right before the signal is decoded, so you can hear it. That way, you'll have a scanner that will pick up the same noise as your receiver. Of course, the downsides are that this requires some electronics skill, and that it's tied to that one type of receiver, on that one channel. And you've ruined a perfectly good receiver :) http://www.bergent.net/SC-DC.pdf has a good talk about the types of interference that R/C receivers deal with. | Our field is on the high plains just east of the foothills near | Denver. The pager antennas are located in the foothills above - and | in the plains to the east below. A hi-gain antenna (yagi...) Yagis are only one of many different types of high gain antennas ... not all high gain antennas are Yagis. Also, the pagers used by restraunts and the like are often on 72 mHz. (I've looked -- they often have the frequency marked on them.) I seriously doubt these use 300 watts (1-5 seems much more likely), but if your plane is closer to a restraunt than it is to you, maybe ... | I've read that repeaters can use 300W of power! I don't see why a pager tower couldn't use more -- it depends on what they have a license for. As for repeaters, 1000 watt repeaters are not unheard of on other bands. As for what these people should do to catch the interference, if that is in fact what it is, is keep scanning, even before there's a shoot-down. Even if nobody is flying. Scan the entire band, and keep doing it. If a signal appears and they can't track it down, ask the local hams for help -- they often love a (useful!) challenge like that. -- Doug McLaren, [EMAIL PROTECTED] If something can go wrong, it w fortune: segmentation fault. core dumped RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off.
RE: [RCSE] Pager? Interference
Doug, The club owns an AERO SPECTRA RC Channel Analyzer. Mark -Original Message- From: Doug McLaren [mailto:[EMAIL PROTECTED] Sent: Friday, October 22, 2004 3:32 PM To: Howard Mark Cc: [EMAIL PROTECTED] Subject: Re: [RCSE] Pager? Interference Do you know what kind of scanners they were using? -- Doug McLaren, [EMAIL PROTECTED] If something can go wrong, it w fortune: segmentation fault. core dumped This message is intended only for the use of the Addressee and may contain information that is PRIVILEGED and CONFIDENTIAL. If you are not the intended recipient, you are hereby notified that any dissemination of this communication is strictly prohibited. If you have received this communication in error, please erase all copies of the message and its attachments and notify Space Imaging immediately. RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off.
Re: [RCSE] Pager? Interference
Mark: Another thing to consider is Radio Controlled or wireless crane/hoist communications systems. I have seen information in publications that some manufacturers were using our 72mHz frequencies to remotely control this type equipment. Might be worthwhile to survey what industrial facilities are in the immediate vicinity of the field. I'm certainly not saying that this is the cause, but at least consider it. I don't believe industry has any general license to use our frequency. Anyone on the exchange ever hear of this situation? Ed Jett Marion, MS - Original Message - From: Howard Mark [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Friday, October 22, 2004 3:26 PM Subject: [RCSE] Pager? Interference At one field I fly at often, we've had problems with interference since the facility was opened 3 years ago. JR receivers seem to have the biggest issues. I believe the early 700's (could be 600's) were worst. I've heard JR has updated the receiver to fix the issues. I mention JR only as information and NOT as a slam. Many of the guys that had problems with JR gear have replaced the receivers with RCD and have had no more big issues. RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off.
Re: [RCSE] Pager? Interference
It sounds very much like you are dealing with pager and/or industrial radio control interference. About the only way to track down the source(s) is to use a programmable scanner hooked to a PC with appropriate software, a uni-directional antenna, a directional antenna, and invest a bunch of time monitoring. Then when you detect a signal in your band you know what frequency and strength the signal is, and if you are quick (!), you can establish the direction the signal is coming from. A few years ago we had a similar intermittent problem at our club field, and being lucky enough to have a retired scientist and Ham as a member, who was also well-equipped with monitoring equipment, we set out to track down the source. We were able to determine it was a high-powered pager tower a couple of miles away (line of sight) and above us, aimed down into our area. We ended up banning one channel and giving warnings on the adjacent 2 channels, and our problems were reduced to noise level. FYI.. Bruce DeVisser - Original Message - From: Howard Mark [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Friday, October 22, 2004 1:26 PM Subject: [RCSE] Pager? Interference At one field I fly at often, we've had problems with interference since the facility was opened 3 years ago. JR receivers seem to have the biggest issues. I believe the early 700's (could be 600's) were worst. I've heard JR has updated the receiver to fix the issues. I mention JR only as information and NOT as a slam. Many of the guys that had problems with JR gear have replaced the receivers with RCD and have had no more big issues. A couple of weeks ago I (ch32) was aerotowing a friend's (Jon) sailplane. He got hit shortly after takeoff (ch44) and also just before landing - causing him to damage a beautiful sailplane. Jon was flying Airtronics gear (Stylus) PPM. Just a few minutes later a pilot flying a 1/3 scale 3D plane with JR PCM reported that he'd had a lot of hits. Turns out he didn't know if the interference was caused by his ignition, setup Or if it was coming from some other source. I witnessed several uneventful flights so I figured it was safe to fly. I fired up my trusty Skybolt and wrung it out for a few minutes. I thought I had a minor hit once - just before the thing dove straight into the ground - full throttle - from about 200 feet. The model exploded and was a total write-off. I've flown this model at the same facility dozens of times before without a problem. I used an Airtronics 660 / RCD 535 in the Skybolt. Of course a frequency scanner showed that my frequency was clean AFTER the wreck. Club members have tried in vain to find the source of the interference. I had not had many problems before I lost the Skybolt - a few glitches that last a second or so - and those are rare. But once Bob Vixie came out to fly there and his Tiger II went wacko on approach. It dove straight at the ground rolling - full throttle, pulled out inverted at about 3 feet and rolled back upright and cut the throttle - all on it's own before giving control back to Bob. Bob was so shaken that he shoved the radio at me and said Here - YOU land it!. Bob had the susceptible gear in his plane. Now to my question. Is it possible that this is pager interference? I've downloaded the coordinates of pager antennas from the FCC and plotted them. Connecting the dots by company reveals three possible sources. Of course I don't know if these are pager repeaters or not. Is it POSSIBLE that our field is in the path of a high-powered pager repeater - and that this could be the source of our interference? Our field is on the high plains just east of the foothills near Denver. The pager antennas are located in the foothills above - and in the plains to the east below. A hi-gain antenna (yagi...) will still probably have a beam width wide enough to cause a problem for anything close to the centerline of it's path. I've read that repeaters can use 300W of power! Any info that anyone can supply would be appreciated!!! - but please facts and NOT just opinions. Mark This message is intended only for the use of the Addressee and may contain information that is PRIVILEGED and CONFIDENTIAL. If you are not the intended recipient, you are hereby notified that any dissemination of this communication is strictly prohibited. If you have received this communication in error, please erase all copies of the message and its attachments and notify Space Imaging immediately. RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED]
Re: [RCSE] Pager? Interference
Pages used to be one of the primary users of our band, they sat spaced 10KHz from our channels. I didn't think that this was relevant any more since everything was cellphone and the like but these frequencies may have got a new lease on life with products like the trafficgauge that provide a realtime congestion displays for motorists. Martin Usher RCSE-List facilities provided by Model Airplane News. Send subscribe and unsubscribe requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off.
