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New Interfering (IX) Signals - "Baby Monitors" using GMRS/FRS

ix interference baby monitor continuous D754 D734 nursing

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#1 intermod

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Posted 29 June 2020 - 05:41 PM

Here in the San Francisco Bay and Sacramento regions we have started hearing a "baby monitor" type devices using GMRS 462 and 467 MHz primary repeater frequencies, in nursing home settings (given the message content).  We are aware of about twenty incidents of this over the past three months, but the rate of occurrence is rising.  The most recent was strong enough to interfere with a CERT/Fire Council repeater out here. 
 
These typically operate during daylight periods, and appear to be continuously keyed for up to 12-16 hours at a time, although background noise, such as televisions, could be keeping them transmitting if set for VOX.  They do not have time-out timers enabled.  These change channels occasionally, but usually end up on 462.625, 462.725, 467.625 and 467.725 MHz.   They use a D754 or a D734 DCS code.
 
This kind of device was explicitly mentioned in past FCC GMRS rulings as it was feared that manufacturer's might use these channels for such things.
 
Given most repeaters here in California are on 1500-4000 ft. mountains, continuous destructive interference will occur to our repeater inputs.   
 
I tried to DF the source of one of these last week, but it was found to be in San Francisco and we ran out of time.  SF is a particularly difficult place to do this due to the density, hills and other sources.  Thankfully these are constantly keyed.  The device I was looking for was horizontally polarized, making it about 10-20 dB weaker when received on a vertical vehicle antenna.   A Yagi in horizontal worked best.  
 
My goal was not to go after the user (they don't know better), but instead get a picture of the device, determine its manufacturer and model number, and establish who is selling it.  As these may be used in nursing care facilities, they will likely have to bring the device out to us to be safe. 
 
Please let us know here if you hear these as we are trying to keep a list of the channels and codes in use so we can identify the specific radio model. 
 
This is clearly in violation of §95.1733(a)(10) and §95.1763© for GMRS, and §95.587(3) for FRS.  It also appears to violate §95.533.  


#2 WPXM352

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Posted 29 June 2020 - 06:38 PM

This is awful. Keep us posted as to what you find. It is amazing what junk gets imported and sold.



#3 WRAK968

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Posted 30 June 2020 - 05:59 AM

Unfortunately many of these devices are likely to be chinese made and the companies won't respond or react to any FCC violations but rather change marketing names as to continue selling in the US. E-bay doesn't help the situation much either.

I have seen several devices from chinese manufacturers ranging from monitors to two-way intercoms which look to operate in the 462/467 range and as you mentioned above, they all operate on a DCS code. Some even advertise that they will work with two way radios, giving the frequency and DCS code in the ad.

In the end, the end user is the one responsible for use and operation of non-certified transmitters. Most times simple education and assistance is all that is needed to get companies in the right direction (Many don't wish to receive a fine, but many more do not want to face the legal ramifications should private personal info be released into unsecured airwaves)



#4 WRAK968

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Posted 30 June 2020 - 06:10 AM

https://www.ebay.com...~kAAOSw0nlehVWI

 

Example of one such device, This unit uses frequencies in the 463 and the 409MHz range. Not exactly gmrs but still a violation as they claim it is FCC compliant.



#5 WQEJ577

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Posted 30 June 2020 - 08:38 AM

I seem to think Retevis has a type-accepted intercom very similar to the one WRAK968 posted. I was digging through the OET site and found it.

 

If I have time I'll go look it up and post it here.


Rich Dunajewski

Founder, myGMRS.com

 


#6 tweiss3

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Posted 30 June 2020 - 09:04 AM

I seem to think Retevis has a type-accepted intercom very similar to the one WRAK968 posted. I was digging through the OET site and found it.

 

If I have time I'll go look it up and post it here.

 

This one? https://www.retevis....ng-device-rt57/

Manual lists Rx in 463.XX and Tx in 409.XX



#7 berkinet

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Posted 30 June 2020 - 09:24 AM

I am not sure if this is the specific "duck" reported by Intermod. But, it walks, swims and quacks like it...

 

https://www.amazon.c...sk_ql_qh_dp_hza

 

The product is described as: Frequency Range: UHF 400-470MHz ,Memory Channel: 16, CTCSS/DCS
Using their programming software, available on request, they say it can be set to different channels and VOX operation can be enabled. If VOX operation is enabled, and there is a constant background source of noise, like a TV, it might appear to be on full-time. Since it can operate off of charger power, it could theoretically broadcast forever.

It sounds like a basic cheap UHF CCR.

 

Any recourse against the seller is probably gaunt to be fruitless, they will just fold their tent and set up a new one.. However, sales channels, like Amazon and eBay may be more sensitive to legal pressure from the FCC.


Everything we hear is an opinion, not a fact. Everything we see is a perspective, not the truth.

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#8 berkinet

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Posted 30 June 2020 - 09:43 AM

...The product is described as: Frequency Range: UHF 400-470MHz ,Memory Channel: 16, CTCSS/DCS....

It is quite possible the seller is trying to operate under FRS rules. Since we do not know the actual output power, it is possible the transmissions do meet the FRS standard.

 

However, there are a couple of significant problems.

 

First, if being used as a monitoring device, one-way transmission is implicit, particularly if VOX is enabled.  But, FCC Part95-B states...

§ 95.531 Permissible FRS uses.

...

(b) One-way communications. FRS units may be used for one-way communications that are emergency messages, traveler assistance communications, voice pages or brief equipment tests.

 

So, the promoted use as a monitor is not supported. However, more problematic is...


§ 95.561FRS transmitter certification.
(a) Each FRS unit (a transmitter that operates or is intended to operate in the FRS) must be certficated for use in the FRS in accordance with this subpart and subpart J of part 2 of this chapter.

and...

 

§ 95.587FRS additional requirements.
Each FRS transmitter type must be designed to meet the following additional requirements.

(a) Transmit frequency capability. FRS transmitter types must not be capable of transmitting on any frequency or channel other than those listed in § 95.563 [The FRS frequency list].

 

So, unless they are lying about the radio's frequency band, there is no way this device is legal. Even then, the specific intended usage is not legal on FRS.


Everything we hear is an opinion, not a fact. Everything we see is a perspective, not the truth.

-- Marcus Aurelius


#9 berkinet

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Posted 30 June 2020 - 10:18 AM

I am not sure if this is the specific "duck" reported by Intermod. But, it walks, swims and quacks like it...

 

https://www.amazon.c...sk_ql_qh_dp_hza

This specific product has been reported to Amazon. Maybe something will happen.


Everything we hear is an opinion, not a fact. Everything we see is a perspective, not the truth.

-- Marcus Aurelius


#10 intermod

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Posted 30 June 2020 - 10:46 AM

Unfortunately many of these devices are likely to be chinese made and the companies won't respond or react to any FCC violations but rather change marketing names as to continue selling in the US. E-bay doesn't help the situation much either.

I have seen several devices from chinese manufacturers ranging from monitors to two-way intercoms which look to operate in the 462/467 range and as you mentioned above, they all operate on a DCS code. Some even advertise that they will work with two way radios, giving the frequency and DCS code in the ad.

In the end, the end user is the one responsible for use and operation of non-certified transmitters. Most times simple education and assistance is all that is needed to get companies in the right direction (Many don't wish to receive a fine, but many more do not want to face the legal ramifications should private personal info be released into unsecured airwaves)

 

Agree that the end-users are actually responsible, but spending time with any one of them to educate / change behavior may not be worth the time.  What often happens is that the radios usually ship with the offending frequencies - and they ship hundreds or thousands of these.  So the key is to head it off at the supply point.  The FCC *will* start sending letters and making phone calls when your information is well-researched and credible.  


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#11 Jones

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Posted 30 June 2020 - 11:05 AM

https://www.ebay.com...~kAAOSw0nlehVWI

 

Example of one such device, This unit uses frequencies in the 463 and the 409MHz range. Not exactly gmrs but still a violation as they claim it is FCC compliant.

 

Wow... That is in NO WAY legal for use in the USA.

 

The 463 (and 468) MHz band is reserved as National Interoperability frequencies for Medical Emergency communications - ambulance and hospital two-way radios. 

 

The 409-414 MHz band is for US Federal Law Enforcement, and "Federal Incident Management - Tactical Interop Communications" - whatever that is, I wouldn't want to mess with it.

 

By the way, there are 20 channels in the 409 MHz band that are known as the "CB" band in China, and they are legal to use there.
 



#12 WPXM352

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Posted 30 June 2020 - 11:56 AM

 

Here in the San Francisco Bay and Sacramento regions we have started hearing a "baby monitor" type devices using GMRS 462 and 467 MHz primary repeater frequencies, in nursing home settings (given the message content).  We are aware of about twenty incidents of this over the past three months, but the rate of occurrence is rising.  The most recent was strong enough to interfere with a CERT/Fire Council repeater out here. 
 
These typically operate during daylight periods, and appear to be continuously keyed for up to 12-16 hours at a time, although background noise, such as televisions, could be keeping them transmitting if set for VOX.  They do not have time-out timers enabled.  These change channels occasionally, but usually end up on 462.625, 462.725, 467.625 and 467.725 MHz.   They use a D754 or a D734 DCS code.
 
This kind of device was explicitly mentioned in past FCC GMRS rulings as it was feared that manufacturer's might use these channels for such things.
 
Given most repeaters here in California are on 1500-4000 ft. mountains, continuous destructive interference will occur to our repeater inputs.   
 
I tried to DF the source of one of these last week, but it was found to be in San Francisco and we ran out of time.  SF is a particularly difficult place to do this due to the density, hills and other sources.  Thankfully these are constantly keyed.  The device I was looking for was horizontally polarized, making it about 10-20 dB weaker when received on a vertical vehicle antenna.   A Yagi in horizontal worked best.  
 
My goal was not to go after the user (they don't know better), but instead get a picture of the device, determine its manufacturer and model number, and establish who is selling it.  As these may be used in nursing care facilities, they will likely have to bring the device out to us to be safe. 
 
Please let us know here if you hear these as we are trying to keep a list of the channels and codes in use so we can identify the specific radio model. 
 
This is clearly in violation of §95.1733(a)(10) and §95.1763© for GMRS, and §95.587(3) for FRS.  It also appears to violate §95.533.  

 

Are they showing up directly on the 467.xxx GMRS inputs or the 467.xxx5 FRS channels? Some repeaters having AFC will pull in an offset channel.

 

Until we figure this out, if the owners are not compliant. Rude sounds.... Oops clean up needed in bed 13!



#13 berkinet

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Posted 30 June 2020 - 12:10 PM

Are they showing up directly on the 467.xxx GMRS inputs or the 467.xxx5 FRS channels? Some repeaters having AFC will pull in an offset channel.

 

Until we figure this out, if the owners are not compliant. Rude sounds.... Oops clean up needed in bed 13!

 

As noted by Intermod above, reports seem to indicate they are on the main 2 watt/(high-power FRS  channels: 1-8 & 15-22). This makes sense since the devices are being advertised as having 1.5 mile range.  

 

As to the on the air response. Besides being illegal, it is unlikely to be very effective. Keep in mind the real issue here is transmitters that are, for all intents and purposes, locked on. And, presumably most receivers will be close to the transmitters, probably in the same building.   So, because of the FM capture effect, the receiving station would never even know you were transmitting.


Everything we hear is an opinion, not a fact. Everything we see is a perspective, not the truth.

-- Marcus Aurelius


#14 intermod

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Posted 30 June 2020 - 12:35 PM

Are they showing up directly on the 467.xxx GMRS inputs or the 467.xxx5 FRS channels? Some repeaters having AFC will pull in an offset channel.

 

Until we figure this out, if the owners are not compliant. Rude sounds.... Oops clean up needed in bed 13!

 

Directly on the 467 MHz primaries.  Listened with various receivers, none have AFC.  Last time I saw AFC was on the Micor repeaters, I think.  Hope none of those remain in operation...they would be almost 50 years old and sliding back and forth with all the FRS traffic.  

 

Some of our users tried to be heard using the same DCS code, but you need to be very close to overcome a 1-5 watt radio in the next room. 

 



#15 WPXM352

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Posted 30 June 2020 - 01:39 PM

Directly on the 467 MHz primaries.  Listened with various receivers, none have AFC.  Last time I saw AFC was on the Micor repeaters, I think.  Hope none of those remain in operation...they would be almost 50 years old and sliding back and forth with all the FRS traffic.  

 

Some of our users tried to be heard using the same DCS code, but you need to be very close to overcome a 1-5 watt radio in the next room. 

 

 I was managing some UHF community repeaters on the Sears Tower back in 1980's. We had interference arriving at the antenna and LNA way up on the top pylon. It had a distinctive tone with heartbeat. HP had marketed some medical telemetry on the UHF splinter channels and those were buried deep in hospitals . Those transmitters were less than 50 milliwatts. The solution was to defeat AFC.



#16 Lscott

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Posted 30 June 2020 - 01:59 PM

Wow... That is in NO WAY legal for use in the USA.

 

The 463 (and 468) MHz band is reserved as National Interoperability frequencies for Medical Emergency communications - ambulance and hospital two-way radios. 

 

The 409-414 MHz band is for US Federal Law Enforcement, and "Federal Incident Management - Tactical Interop Communications" - whatever that is, I wouldn't want to mess with it.

 

By the way, there are 20 channels in the 409 MHz band that are known as the "CB" band in China, and they are legal to use there.
 

The usual non compliant consumer marketed Chinese wireless crap being sold in the US. Some years ago there was a problem with “high power telephone wireless handsets” that claimed 1 mile plus range. Turned out they were operating on the Ham 2 meter band. After a series of complaints to the FCC the issue was addressed.



#17 tweiss3

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Posted 30 June 2020 - 02:20 PM

The usual non compliant consumer marketed Chinese wireless crap being sold in the US. Some years ago there was a problem with “high power telephone wireless handsets” that claimed 1 mile plus range. Turned out they were operating on the Ham 2 meter band. After a series of complaints to the FCC the issue was addressed.

 

Unlicensed user + telephone interconnect. Thats a double whammy.



#18 intermod

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Posted 30 June 2020 - 06:46 PM

 I was managing some UHF community repeaters on the Sears Tower back in 1980's. We had interference arriving at the antenna and LNA way up on the top pylon. It had a distinctive tone with heartbeat. HP had marketed some medical telemetry on the UHF splinter channels and those were buried deep in hospitals . Those transmitters were less than 50 milliwatts. The solution was to defeat AFC.

 

That would do it...good solution.   I believe that was designed in the repeaters to provide more forgiveness to the UHF mobile radio transmitters that were prone to drifting.  But in 1980 things were quite stable.

 

G



#19 n4gix

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Posted 04 July 2020 - 01:21 PM

RT57

Output Power 0.5 W
Channel Stability ±5 ppm
 



#20 KeithKenobi

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Posted 09 July 2020 - 12:04 PM

YES! I am hearing a LOT of these in the Santa Cruz area and Monterey areas.

On REPEATER INPUTS like 467.625 as well as random FRS/GMRS channels. 

Always with a DPL like 734 

They are copy-able for MILES, sometimes 5! 

I have not had the time to track them down to a specific building, BUT if we can make a list of approx locations, maybe the FCC will make a trip.

Unfortunately, they seem to change frequencies, but maybe we can log locations.

The FCC does respond to interference reports.

Keith

 







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