McLennan County Announces Digital Migration

[Ensnared]

Flip Switch Activation?

There are two main types of encryption, Advanced Digital Privacy, and AES Hardware. The ADP is a Motorola only encryption that now comes standard with all APX radios. We use AES Hardware as it is a P-25 National standard which allows secure communications with other agencies. I assign specific Talkgroups to use encryption so when that talkgroup is selected the encryption is automately turned on. Just to let you know, I dis-like encryption as it is difficult to manage, and program. This is expecially true when another agency is involved like US Marshals. I don't see them using ADP for several reasons. You can only select one or the other, can't have both types turned on, and ADP still has to be programmed and they don't have this capability.

Larry

So, when these 18 radios want to go to their "installed" encryption, do they go to TG35 for privacy? To me, this would be a dedicated encrypted channel. Or, do they just turn it off by flipping the switch? I am assuming that the flipped switch applies to the standard ADP alone.

I have given up listening to the DEU units because I've never ever heard clear transmissions on them.

If TG35 is fully encrypted, I will submit a change to the RR DB.

I was laughing at someone the other day who talked about how easy it was to break encryption. He stated it could be done with a baby monitor or something. I believe he was referring to the University that exposed a flaw in the P25 security. However, I am sure that this has been addressed by Motorola.

Also, when I was monitoring TxWarn P25 when the task force was using "Digital J", I heard a federal agent talking about them having an encrypted repeater. He stated it was deep & rather difficult to find.

I still laugh when I recall what that one study found about Homeland Insecurity users not being able to operate their radios. I believe 1 out of 279 users were able to do so.

 

[SCPD]

I might be wrong, If I am someone will stand up and point a finger at me BUT I believe the encryption algorithm is written to the radio not to the site controller or repeater. Its the same as Rolling Inversion, the radio has a board implanted then the inversion mode and code is written to the radio via. radio software. You can have a dedicated TG for encryption and also have an encryption on/off button which wont bypass a dedicated TGID. Most likely TG33 is set to encrypt on the radio only.

 

[Ensnared]

TG Specific

I might be wrong, If I am someone will stand up and point a finger at me BUT I believe the encryption algorithm is written to the radio not to the site controller or repeater. Its the same as Rolling Inversion, the radio has a board implanted then the inversion mode and code is written to the radio via. radio software. You can have a dedicated TG for encryption and also have an encryption on/off button which wont bypass a dedicated TGID. Most likely TG33 is set to encrypt on the radio only.

I wonder if this means that other radios, outside of the 18, can transmit in the clear on TG 33?

 

[Larrybl]

Encryption

Unfortunally I can't point you to the web site describing AES encryption.....

NIST Closed, NIST and Affiliated Web Sites Not Available
Due to a lapse in government funding, the National Institute of Standards and Technology (NIST) is closed and most NIST and affiliated web sites are unavailable until further notice. We sincerely regret the inconvenience.

Yes other users can transmit in the clear on these Talkgroups (no AES in their radios) on 1D, 1E and 3C. The AES radios automatically select AES when these talk groups are selected.

AES is 256 bit hardware encryption that is installed in the Suscribers, not the repeaters.

Larry

 

[Ensnared]

Understood

Yes, I also encountered a shut-down of the FCC home page.

Thanks for clearing this up for those interested in TG35. At least the Waco Information officer kept his word stating that there would be encryption on a few Talk Groups. When he commented on the Waco PD FB page, he mentioned the likelihood of there being a encrypted SWAT channel.

 

[Ensnared]

Spotty Reception Waco P25

For the past few days, I have been experiencing poor reception on the Waco Public Safety P25 TSYS. I changed out antennas & have noticed a slight improvement using the RS 800 mhz antenna. Has anyone else noticed poor reception on this system as of late?

 

[Ensnared]

Waco Public Safety P25 Fixed

Due to the poor reception I was experiencing on the Waco PS P25 TSYS, I adjusted various settings listed under "Optimizing Scanner Parameters" in the Easier to Read guide. Now, this system is coming in better without any cutting out.

I nearly freaked out from making a huge mistake. I popped the back of my PSR 500 to see if the BNC screw was loose; however, when I did, I pulled on the white wire attached to the bottom of the radio. Afterward, I made adjustments to my V folder for Waco. I also made the same adjustments to a V folder I have set aside for someone I help to program his Pro-106. He prefers to have all LED turned off without any alarms. Without paying attention, I inadvertently loaded his V-folder instead of mine.

So, when I turned the radio on, the lights & alarms were inoperative. I attributed this to my tinkering in the back of my radio. I am radio-repair challenged. As a last resort, last night, I thought I would try to reload the Waco V-folder. I was very relieved to see the lights and alarms fully functional once again.

Now, the radio is working great.

Adjustments made:

TGRP Pri Int set to "off."
In band Sq Timeout set to "7"

 

[Gman3939]

Very poor reception!

 

[Ensnared]

Thanks

Thank you very much for the feedback on this system. I have been noticing an increased frequency of drops. It seems as though the signal is strong & then fades at the end of the transmission. I've noticed a deterioration since it was first installed. So, this is the first time someone has found the same, poor reception.

 

[Larrybl]

Waco is now simulcasting.

On Sunday April 13th we added the 12th Street tower site and now are simulcasting from both towers. Long story, but in a nut shell, when we were modifying our license WNSW338 to add the additional sites, we had to lower our ERP's due to a FCC Rebanding freeze which is still in effect for our area. I do not know how scanners are affected by receiving signals from multiple towers, but it has seemed to improved our radio reception.

Larry

 

[nd5y]

I do not know how scanners are affected by receiving signals from multiple towers, but it has seemed to improved our radio reception.

Simulcasting P25 signals generally makes scanner reception worse and real radio reception better. There are several threads about why scanners can't handle P25 simulcast signals properly in the Uniden RS and GRE sub forums.

 

[Larrybl]

LSM and CQPSK

During our conversion to Simulcast we did change the modulation to LSM "Linear Simulcast Modulation" and I have located several threads on this subject. http://forums.radioreference.com/pr...linear-simulcast-modulation-difficulties.html

Larry.

 

[Ensnared]

ERP?

On Sunday April 13th we added the 12th Street tower site and now are simulcasting from both towers. Long story, but in a nut shell, when we were modifying our license WNSW338 to add the additional sites, we had to lower our ERP's due to a FCC Rebanding freeze which is still in effect for our area. I do not know how scanners are affected by receiving signals from multiple towers, but it has seemed to improved our radio reception.

Larry

I am attempting to synthesize this information into my smooth fissure-less gray matter. I don't understand what "ERP's" means. When I put this in Google, odd things surfaced. I am assuming this has something to do with emissions power.

So, here is my next question. When the rebanding freeze lifts, will full power resume?

It helped me to adjust various parameters on my scanner such as TGRP interruption & In band squelch time out.

Thanks for the information because I thought something was amiss. I suppose I am going to be buying a scanner in the near future that handles simulcasting problems better than my PSR 500.

 

[Larrybl]

ERP

Only the Effective Radiated Power (ERP) was changed for the 12th Street site, the HOT site stayed the same. I think the bigger issue is the scanner's ability to decode the new Linear Simulcast Modulation (LSM)

 

[nd5y]

ERP is Effective Radiated Power.
https://en.wikipedia.org/wiki/Effective_radiated_power

 

[Larrybl]

Great Wiki Reference

This may provide some help.

Simulcast digital distortion - The RadioReference Wiki

Larry

 

[Ensnared]

Power Resume?

I'm aware of the problem now, but what happens when the rebanding freeze goes away? Will the power be increased or returned to what is was before?

 

[Larrybl]

I'm aware of the problem now, but what happens when the rebanding freeze goes away? Will the power be increased or returned to what is was before?

Once we have all three sites up and running, we will evaluate the coverage that is provided within the City. If the coverage is acceptable we will most likely leave the ERP's as is. With Simulcast too much ERP can be a bad thing, expecially if the towers are close together like ours are.
If we do need to increase ERP, then it will need to wait till the freeze is over, I think this is supposed to happen around 2016.

 

[Ensnared]

Differential Reception

Once we have all three sites up and running, we will evaluate the coverage that is provided within the City. If the coverage is acceptable we will most likely leave the ERP's as is. With Simulcast too much ERP can be a bad thing, expecially if the towers are close together like ours are.
If we do need to increase ERP, then it will need to wait till the freeze is over, I think this is supposed to happen around 2016.

I have noticed this while monitoring the system. Some of the time, the signals come in, loud & clear. At other times, it sounds like they are more distant. I would guess this is a symptom of simulcasting.

So, I will continue to adjust my radio to hear this system. I am looking at my variety of antennas that might help with reception. I suppose I will be trying my Radio Shack 800 mhz rubber antenna next.

Simulcasting issues are a problem for many who attempt to monitor GATTRS in the Austin area.

 

[Ensnared]

Phase II Scanners for Waco P25

Simulcasting distortion has been a big problem for certain radios; however, I have heard that the GRE PSR 800 & the new Phase II Unidens handle simulcasting better.

So, I am asking to hear from those who monitor the Waco Public Service P25 system with Phase II scanners. Please, provide feedback concerning your experiences in monitoring this system.

The ideal situation would hearing from someone with a Phase II scanner before and after the recent changes were made in the system.

Hopefully, purchasing a Phase II scanner will help.

At present, I am using a PSR 500. I am saving up my bucks to buy a Phase II. Hopefully, Whistler will deliver the goods.