Lscott
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Posts posted by Lscott
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3 hours ago, davidotoole said:
Oh, thank you for fixing this error in my brain
. I wonder if you could explain why this is?
The radios we use employ FM, frequency modulation. In other words the transmitted frequency is varied to convey the audio information. The amplitude of the transmitted signal, power, is not used to convey any audio information.
This is why you see references to wide-band verses narrow-band on these forums. What is being referred to is how much the transmitted frequency varies, called deviation, for a given audio signal level. The wide-band can vary the transmitted signal by as much as 5KHz, while a narrow band signal will only vary by 2.5KHz.
If we use wide-band on transmit to communicate with a narrow-band radio the audio will sound very loud and likely will be distorted. The reverse case a narrow-band radio transmitting to a wide-band radio the audio will sound very weak, low volume. This is why it's important to ensure that all radios are set to use the same bandwidth, deviation, and thus the FCC's comments you got.
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1 hour ago, davidotoole said:
My main reason for limiting to 2 watts when communicating with FRS radios is to avoid having FRS radios not be able to respond to GMRS when just out of transmit range, and so that the volume difference is eliminated.
The power level has nothing to do with the audio volume when using FM for communications.
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12 minutes ago, davidotoole said:
I checked and my Baofeng GMRS-9R's allow setting narrow band on channels other than 8-14, so I'll program that (and 2.0 watt power level) and we should be good to go for GMRS/FRS! Thanks everyone for your help.
If you have a GMRS license there is no requirement you have to use 2 watts or less on 1-7 and 15-22. That ONLY applies to FRS radios. GMRS radios can use up to 5 watts on 1-7 and up to 50 watts on 15-22, and that includes when talking to FRS radios.
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4 hours ago, davidotoole said:
I spoke with an FCC representative on the phone today, and came to the understanding that we could communicate between GMRS and FRS radios provided that:
- We must use only channels 8-14
- We must limit power to no more than 0.5 watts.
That's not a "requirement" as such. It's in the rules that GMRS radios must use narrow band FM on channels 8-14 and no more than 0.5 watts. This is the exact same technical requirements for FRS radios. The FCC rep likely mentioned the above because the two radio services would be compatible on a technical level.
You can legally program your GMRS radio to use narrow band FM on all channels thus you can use any of the 22 to communicate with FRS radios. The radio I use, Kenwood TK-3170, has "zones" which are logical grouping of memory channels. I have one zone programmed for wide band when talking to other GMRS radios, and another zone with the same channels programmed for narrow band to talk with FRS radios. Since the radio can't be turned down to 0.5 watts, minimum is 1 watt, I don't use 8-14 to talk with FRS radios.
- Sshannon, davidotoole and WRUU653
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21 minutes ago, Sab02r said:
Thanks for sharing that info Lscott! This will the fourth or fifth time I have heard mention of tire pressure management system interference...and not always the same auto manufacturer..
I am compelled to ask, regarding the car alarm failures, do you know if this was this a permanent failure or a temporary condition?
In either case I can see how people could be a little miffed that their car alarms could be so easily and anonymously defeated.
My understanding was it only occurred in the vicinity of the ATV site. Once the affected systems were far enough away they were OK.
I guess what it came down to the designers didn't do enough research when selecting what frequency, band, to use for their product. The radio spectrum is very complex with the same band being used for different purposes, shared, and sometimes they don't play together very well.
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6 hours ago, WRWM850 said:
Pretty new to 2 way radio...Been rocken the Baofeng and I'm ready to step it up.
I'm leaning towards a commercial radio that I can use on gmrs frequencies leaning towards a motorola 5000 (and yes I know that is not a legal gmrs radio that's not what I'm asking)
I really value reliability and and would like something multi purpose, one concern is that they are getting old, would it be a bad move to spend that much money an older radio?
I'm currently considering buying an xts 5000 military version uhf2 with battery and charger plus some programing for 400$
a couple others that a have considered are EF Johnson 5100 ant Anytone AT-D878UVII PLUS
Anyone have have any advice on this?
Have you considered some less expensive radios than the above? There are other analog only commercial radios that will take a beating and keep working. Myself I carry a Kenwood TK-3170. You can can find them for very reasonable prices used and it has Part 95 certification too.
http://www.swscomm.com/kenwood/TK-2170_3170.pdf
There is also a version with trunking, TK-3173, which you won't use on GMRS, but programs the same as the 3170 and uses the same cables and software.
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These comments point out an interesting issue if I understand things right. Most, if not all, electronic products are sold with FCC Part 15 compliance. A section in that part basically says the device accepts all interference even if it causes the device to malfunction. If it does then contact the manufacture.
Now try to explain that to your neighbor when they says it's YOUR problem to fix. Nope, so long as your radio meets all FCC certifications. Another reason to be sure your radio is Part 95 certified.
A case in point.
Years back people were experiencing car alarm failures around the I-75 and 14 Mile intersection close to where I work. The FCC was notified. The issue was traced to a Ham ATV transmitter on top of a tall senior apartment building a couple of miles west of the location above. The FCC shut the site down while they did their investigation. They found everything complied with all technical requirements and allowed the site to resume normal operations. The ding-dongs had put the alarm system on the 70cm band. I believe there is a provision in the rules for this were the equipment manufactures can use 433MHz.
https://www.edn.com/using-433-mhz-for-wireless-connectivity-in-the-internet-of-things/
The head guy at the alarm company asked one of the site's equipment owners in for a talk. He asked how much power they were running. The answer was about 100 watts. Then he asked the second one. How much CAN they run. The answer was 1500 watts. The owner I was talking to telling me this story said the alarm company guy almost crapped his shorts.
Then he proceeded to tell me another story about how Chrysler, as it was known at the time, had their tire pressure sensors malfunction. They were running tests on them and had the problem again in about the same area. In their case they figured out the cause and understood it was their problem to fix.
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25 minutes ago, WRUT935 said:
I just for this 50W 50 ohm dummy load. XRDS-RF from Amazon. I directly connected it to my SureCom meter, no cables and no adapter needed. I keyed up and read both wattage and SWR, the SWR shows 1.7 which is higher than what I get through my outside antenna with 45 feet of cable! Is this just a bad dummy load or am I missing something. I expect 1.1. I measured the resistance using a digital ohm meter and it read 49 ohms.
Why am I checking SWR? To use the dummy load to measure line loss of the cable. Professor Ed Fong told me it would be good reference to measure the SWR introduced by the cable and measure again with the antenna. This way, you can tell what is contributing to the overall value.
I know there are a lot pricier dummy loads, is this brand/unit bad?
I'm guessing the dummy load looks something like this?
I wouldn't worry about the resistance reading of 49 verses 50 ohms. There is a tolerance on the accuracy of the dummy load and the meter itself that likely accounts for the difference.
Dummy loads also have a frequency range they are designed to work over. High quality ones may even have a datasheet showing the expected match verses frequency. The one you have may just be at the edge of the range, but without further info I can't really say much at that aspect.
The Surecom meters people have reported funny behavior. One of them is a change in SWR with a change in power level. Theoretically the SWR should not change when the power level changes.
The other thing with SWR has to do with the coax cable. A longer cable will absorb more of the reflected power from the antenna end back to the transmitter. With the meter at the transmitter end this makes the SWR look better compared to making the measurement right at the antenna. I've taken advantage of this to get a match under 2:1 on a radio when using an antenna outside of it's specifications and the loss in power, on the coax to the antenna, is the price paid for the benefit. There is no free lunch.
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2 hours ago, Sshannon said:
I actually do care about the rules. I care that we explain them accurately when asked and that we explain why we have the rules we have.
But I don’t like to see us whip them out as a scolding remark to someone who is just getting started and has just asked for help.I think most of us on this forum do as well. I try to remind people of the rules without being an A-Hole on the issue. People are adults and will make their own decisions, I just want to help them make an "informed" one. So long as I did what I think is the proper thing to do I let others make their decision whether I agree with it or not.
- wayoverthere, axorlov, WRQC527 and 2 others
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17 hours ago, nokones said:
Shipping from Canada isn't too bad if it is shipped through the US Post Office. It seems that the eBay sellers from Canada, near Toronto, have some ability to get their wares to the US Post Office system for shipping. I have ordered stuff and it usually took about a week.
I remember flying out of the Toronto airport years ago back to the US. Weird part was I went through US customs at the airport before boarding the flight! Arrived at DTW as a domestic flight. I guess that was the point.
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41 minutes ago, Sshannon said:
Almost nobody truly cares.
That might be true with the UV-5R. On the "Spurs" thread I posted a file with the spectrum of what the output looks like. Various Hams know how dirty those buggers can get and won't use them, at least on a regular basis.
I had a buddy that tried the mod for the BF-888, another CCR, 16 channel UHF radio. The mod allowed the use of VHF on the radio for the lower 8 channels. He transmitted on a 2M frequency from our south building while I monitored him from our north building. Sounded OK. Then I tuned to the exact 3'rd harmonic of the VHF frequency, which put it on the Ham 70cm band. I heard him there just fine too, and the audio was VERY loud. The reason for that was the deviation on VHF is now 3 times that on UHF. Well that ended the experiment and he disabled the mod. Output of the radio was VERY dirty, spectrum wise, on VHF.
There is a reason why the FCC requires certification of radios. It's not just about what frequencies the radio can transmit on. The radio has to be a "good neighbor" and play nice on the air and not interfere with other users because the transmitter is a POS.
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1 hour ago, Smitty74 said:
I have a dual band comet antenna meant for automotive use. Its like 4 foot tall. If I put it on a "lip mount" base on the edge of my car hood, is the fact that I dont have a good ground plane going to cause me problems? I tried hooking the antenna up to my SWR meter with it just sitting in the middle of my driveway by itself, and I was getting a 1.15 reading. How critical is a good ground plane? am I losing signal? am I going to damage my equipment? It seems like it doesnt need it, and I definitely see lots of other people using these kinds of mounts.
If the SWR looks good you most likely won't damage your radio. The ground plane will influence the direction of maximum signal. That's usually in the direction of the largest area, metal, around the antenna. With a lip mount the signal strength will be higher towards the side of the car with the hood. How much difference that makes is hard to say.
If you really want to know just do some tests. Have a buddy a few miles away monitor your signal level on his radio, not the audio, with the signal strength indicator on his radio. Most radios have one, usually a simple bar graph type. Then turn your car so its in a different orientation relative to you buddy's radio, transmit and have them check the signal strength. This would be easy to do in a parking lot. Doing this while driving around introduces too many other variables that affect the signal strength. If there isn't much or any discernible change then don't worry about it.
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2 hours ago, Sshannon said:
When repeaters are linked like that do they also incorporate voting?
As far as I know these don't, they're on different frequency pairs. It's strange because when somebody is on each repeater you can hear two talking at the same time. You don't get the weird noise that's typical when two FM stations key up over each other.
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2 hours ago, JB007Rules said:
Ebay - Old Toughbook.
I found some nice functional desktops while walking at night through an apartment complex. They were just sitting on the ground next to the dumpster. Can't beat free. Some still had the hard drive installed with the OS on it.
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1 hour ago, Guest Hobbyaddict1 said:
Popped back on again to peruse since it has been a while... Seen my original posting and additional replies. A family member is going to be picking up a radio and I have been scanning and picking up more chatter recently. Seen the possibly of hitting the Troy repeater and another in Detroit so once again started to read up on repeaters. Thanks for the feedback...
-Ed
The Detroit and Mount Clemens repeaters are linked. My understanding is the group that owns them is planing on another one in Pontiac. The Troy repeater is a stand alone.
One other thing there is a repeater at the Lakeside Mall, maybe good for 4 to 5 miles. It's used by the mall's house keeping staff. Funny thing is their license to use it expired on 10/2015 and was NEVER renewed. I double checked that on the FCC's database. They lost any legal ability to use it, but they continue to do so. It's on the same frequency pair as the Troy repeater but uses a different tone, 186.2Hz. If it got high-jacked I guess they can't complain without the FCC asking why they're on GMRS without a license. Oops. The mall security sometimes call them on it, or the other way around too.
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1 hour ago, zzz said:
Can we please get rid of stupid daylight saving!?!?!?
I think they introduced a bill in congress to make daylight saving time permanent.
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On 3/9/2023 at 11:56 AM, Sshannon said:
One of the very best chief engineers I ever worked under had no college degree and no P.E. He had been trained in communications by the US Navy, and he had the knack.
I know people who can calculate anything, but I wouldn't trust them with a screwdriver. They might hurt themselves.
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On 3/10/2023 at 8:23 AM, tweiss3 said:
I also know plenty of other engineers in adjacent fields that the PE is not needed in their role for their engineering practice, and therefore may never get the licensure
I think it's become common, if not required, for engineers to sit for the initial PE exam to graduate at many schools.
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42 minutes ago, WQWX838 said:
True that is... The purpose of a decent program is to build a solid foundation.
I remember to this day what one interviewer told me during one of my job interviews out of school. It's as true to day as it was then. He said "All the degree proves is you have the ability to learn."
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On 3/10/2023 at 12:22 PM, marcspaz said:
Just so you (and others) understand, I am not upset/mad/whatever with you or PE's in general. I also hope you don't get offended by what I am typing... my goal is just a conversation. If we end up disagreeing, it is what it is...
I've had several good chuckles with my buddy. We both have our EE degree's. Where he's at they employ a lot of EE's with MS and PhD's. He says the guys come to him and ask how to do simulations, he has a lot of experience using Saber, which by the way is a heck of a mix mode complex simulator. I have to laugh because people with more degrees than a thermometer are asking him how to do stuff.
We had a Chinese PhD work in our department for several years. One day a board experienced a failed LED on a board he was working on. The guy spent some time downloading data sheets for LED's looking for a replacement. The Lab manager simply asked him why he didn't just get one out of the parts drawer and replace it. Sad but true.
The education, or lack thereof, people are getting in schools is shockingly poor in some cases. We were looking for somebody to do embedded programming. Had a lot of candidates with graduate degrees apply. One of the tests required the candidate to write some code to turn on an LED. We even asked them what processor and or development environment they have experience using, then had it setup when they arrived. Shockingly most couldn't do it! Some of the more interesting questions I asked was how do you turn two LED's on "simultaneously", nobody got that right. The idea was to see how well the candidate understands the connection between what the software does and how it affects the hardware. This was key to doing debugging on real hardware. You have to walk on both sides of the street so to speak, software and hardware.
We hired a young female EE out of school. She has been learning how to do schematic entry and PCB layouts. I told her the real learning comes when the prototype board she did arrives and she needs to get it working on the bench. That's when you learn where you made all your F'ups.
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29 minutes ago, gortex2 said:
I know this has been a hot topic for months on this forum but I'd be more worried about the amount of un-licenced folks using GMRS.
It'll end up like 11M CB. FCC gave up chasing down everyone failing to ID and just made it a license by rule, i.e. license free, service. Less headache for them.
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8 hours ago, ian3211 said:
Just wondering what some good mobile equipment yall reccomend. Just got my license and looking to install in my jeep and work truck.
To continue with the discussion you have to decide if you want to go with purposely built GMRS radios or commercial radios that can be programmed to operate on GMRS.
The purposed built radios are generally of Chinese manufacture and are affordable. The programming software is available and mostly easy to use.
Looking at commercial radios typically means buying used equipment. Programming commercial radios is not like Ham gear or the purpose built GMRS radios. There are more options, many you won't need, and a steeper learning curve. The advantage is you have a radio you can tailor to you preferences better.
If cost is a factor there are some budget friendly radios to be found in both areas.
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7 hours ago, ian3211 said:
Just wondering what some good mobile equipment yall reccomend. Just got my license and looking to install in my jeep and work truck.
How big is you wallet? Some of the guys here run radios in the $2000 to $5000 plus range, top of the line commercial grade multi-mode analog/digital new and used equipment.
. I wonder if you could explain why this is? 
Interoperability between separate FRS and GMRS radios
in FCC Rules Discussion
Posted
Wrong. I've operated VHF and UHF FM for over 20+ years. It doesn't work that way. If you want to talk about SSB on 2M that's a different story.
https://en.wikipedia.org/wiki/Frequency_modulation