My growing collection of unusual noises.I created this page to help my friends with scanners & ham radiosidentify the growing number of new & unusual sounds they might hearwhen monitoring outside the amateur bands.I'm always looking for new additions to this page - if you havehigh-quality audio recordings that you want added to the databasehere.Do note-mail me with questions like 'what is this sound'? - if it does notremotely sound similar to anything I have posted here, I won't knoweither!All sounds are in MP3 format. Click on the title of each to playthem. These sounds are publicdomain, and may be used by anyone.

• Baofeng P25

If you plan to use these forcommercial purposes, please have the courtesy to give me credit asthe source.Section 1 - Unit Identifiers-This is the most common form of unit ID found in public safety. Thisis either broadcast at the start or the end of a unit's transmission(or both, if you so choose to have it programmed that way). Theuser's radio can also be programmed to(toremind the user to wait before speaking, as the unit's mic is notactivated until the ID is sent). (ThanksGreat-Dane & Vinnie!)- This added feature ofthe MDC signaling system is designed to allow a properly programmedradio to mute the ID signal part of the transmission. The raw burstof data tells the radio to mute the speaker audio for apre-determined length of time (usually 400 or 500 ms). If the radiois programmed correctly, the end-user (or dispatcher) would not hearthis sound at all, only the person's voice.- This sound is most commonlyheard in a police cruiser or ambulance cab.

What you are hearing isthe very end of the 'wait tone' echoing off the inside of thevehicle and being picked up by the mic. Also, there areseveral Motorola radios that emit an 'ok' beep, just like a keypress, when the PTT is used. Certain models of the Maxtrac's and'Pro' series radios were famous for this.- This is analternate form of the same protocol used in MDC-1200, but at only600 baud. The FDNY was a primary user of this format before theirrecent radio system upgrades. (Thanks Matt!)- ATIS standsfor Automatic Transmitter Identification System. Itis predominantly used by marine vessels on inland waterwaysthroughout Europe. This was a signaling format available in the U.S.on the HT1000 & VISAR, along with MDC & STAR.

It is based on the. (Thanks Greg!)- This isan older form of unit ID by Motorola. This is actually aslower-speed data transmission rate than MDC-1200, and what makes ittruly unique is that the actual sound of the ID varies when youchange the ID code. Baltimore FD and LAPD used to use this form ofID before they both went to digital.- Thisform of unit ID was General Electric's answer to MDC-1200 when theywhere still involved in the 2-way business (before selling thatdivision to Ericsson).- I recorded this while monitoring Voorhees PD in CamdenCounty, NJ. Only about half of the patrol units on a shift had thisat the end of their transmissions.- This is a simplestream of usually 4 or more DTMF tones used to ID the radio that istransmitting. (Thanks Greg!)-FleetSync is a digital messaging & identification protocol developedby Kenwood that is used in their line of radios. It it quite similarto Motorola's MDC, but has many more capabilities.

Thisis an exampleof what it would sound like if the feature would be used to send aunit-to-unit message, GPS location burst, etc. ( Thanksto Rich, N2DLX). Here is an ofFleetSync in the more common 1200-buad mode.(Thanks Augy!). Here is a in thelesser-used 2400-baud mode. (Thanks Augy!)- MP7 is thedigital identification protocol used on MPT1327 trunking systems. ( ThanksAdam!)- This isHytera's version of Motorola's MDC1200.

The HDC1200 system in Hyteraradios is fully capable of decoding & displaying the data fromMotorola radios, even though the two systems sound different overthe air.Section 2 - Voice Scrambling & Encryption- This recording is from the Gloucester Twp. PD in Camden County,NJ. The dispatcher usually transmits a short warning tone & thencalls the units she needs to speak to in 'secure' mode. As you canhear, the units in the field respond back to dispatch 'in theclear'. Gloucester Twp. Uses this only as needed, and I've neverheard any department use this full-time.- This isanother format of analog encryption designed by Motorola that wasdesigned to have greater range that standard DES before the signalbecomes unintelligible. As with all analog encryption formats, therecovered audio is less than desirable.

( ThanksNick!)- This is what encryption sounds like on a radio capable ofreceiving FDMA P25 audio. This was recorded from a Motorola Type-IItrunking system, but the sound will be similar on a Phase-I P25system.-This is what encryption sounds like on a radio capable of receivingTDMA P25 audio. This was recorded from the new Berks County, PA700MHz Phase-II trunking system. The audio appears to have more of a'sweeping' sound, and is less 'guttural' than when used on FDMA.- This recording is of AES encryption being used on theMiddlesex County, NJ EDACS system (ThanksGreg!)- Thisis a sample of encryption being used on Aegis digital voice.is what it soundslike decoded by a proper receiving radio.(Thanks Greg!)- This is aproprietary 64-bit encryption used on older GE radios(Thanks Ray!)- This recording is from a conventional UHF channelthat is shared between Woodbridge & Perth Amboy PD's. If anyone canhelp identify what this is, it would be greatly appreciated! ( ThanksGreg!)(Thanks Nick!)(Thanks Ray!)- This is what it sounds like(Thanks Nick& Ray!)- As sampled from the PD782 handheld radio.(Thanks RayI)- Thisis the 128-bit encryption featured on the new Tytera MD-380 portableradio (Thanks Ray!)Section 3 - Digital Voice Formats- This was Motorola's first digital voice solution marketed underthe ASTRO name.

This was a in-house modification to the Vector SumExcited Linear Predictive standard that was used in the first TDMAcell phones. Motorola also modified this into the IDEN format thatis used by NEXTEL phones (see below).

Very few jurisdictions usethis type of system anymore (Trenton, NJ & Cleveland, OH). This isnot a Project 25-compliant system, and cannot be picked up on anyknown scanner. Here is aof decoded audio. These two new samples are of VSELP being,.

(Thanks Greg& Nick!)- This is Motorola's current ASTRO voice format offering. This typeof emission is known as C4FM, and the technology in use is the IMBE(Improved Multi-Band Excitation) vocoder from.This is a much betterof decoded audio from the Bucks County, PA 500 MHz trunk system.There are almost half a dozen manufacturers that produce radios thatare capable of 'Conventional P25 Operation' now, so this signalformat is no longer exclusive to Motorola.(Thanks Nick!).This sample was made via a logging recorder equipped with anIMBE vocoder. This was a portable transmitting from inside avehicle.

(Thanks Ragan!)- This is what therepeaters on a Phase-II (TDMA) trunk system transmit on the voicechannels when a conversation is in progress.(Thanks Augy!)- This is the current form of digital voice originally developed byEricsson. This is also an IMBE signal style, but is not Project 25compliant (whereas Motorola's is).is an updated sample from the Middlesex County EDACS system There iscurrently no scanner or receiver that can decode this. Here is anthat shows the slight change in the raw audio when the signal isencrypted.(Thanks Greg!)-This was the first-generation digital voice solution from GE. This format is not well liked because the decoded voiceleaves much to be desired. It is not Project 25 compliant, nor canit inter-mix with ProVoice. As with ProVoice, there is no scanner orreceiver that can decode this.

Here is aof the decodedaudio. (Thanks Greg!)- This is the new digital audio format in use by the D-STAR amateurradio system. This is what you would hear if you came across aD-STAR repeater with a regular analog amateur radio.

This is anvocoder that uses themodulation style (similar to the world-wide GSM cell phonestandard).- This is KC5ZRQ testing the outer range limits of D-STAR vs. AnalogFM on simplex.

This is a pretty impressive example of how D-STARwill hold it's 'intelligibility', while the FM capture degraded to apretty bad level.- The is a brand-newdigital format being co-designed by Kenwood & ICOM that is gearedtowards the business sector. It is designed for those that want tomeet the up-coming FCC mandate for 6.25KHz channel spacing, butthat can't (or don't) want to move to the APCO P25 Phase-IIequipment that will soon come to market.

The format is based on theAMBE+2 vocoder (similar to ICOM's D-STAR), but uses a 4-levelFSK waveform (FDMA). The radios are capable of narrowband analog, alongwith 12.5 KHz & 6.25 KHz digital emissions. Kenwood is offering thesystem under the name, and the radios are capable of both conventional &trunking operation. The attached sound file contains all of theformats the system is capable of producing, including the raw datastreams of both digital formats.

(Thanks Rich!- Audiois credited to David Sterrett,N1DAS)- DMR stands forDigital Mobile Radio, and it is an open standard created bythe ETSI for professional mobile radio users worldwide. Motorolabrought this technology to market in the US as MotoTRBO, but therenumerous radio manufacturers producing equipment now. It is based ona 2:1 TDMA format that uses the AMBE+2 vocoder & a 4-level FSKwaveform. There is now a substantial presence in amateur radio ofthis format. This is what the signal sounds like when used inthrough a repeater, andwhen usedsimplex (talk-around) mode. ( Thanksto thegroup, Jerry, & Nick for the audio!)- This is adigital format used by Motorola DTR-series personal/jobsite portableradios. It utilizes frequency-hopping spread-spectrum signaltechnology (VSELP audio at 11 hops per second) on the 900MHz band.

It is near impossible to get a copyof the raw audio without a service monitor due to the FHSS signal.The Nextel off-network 'DirectTalk' technology is based off of thissame design, but the two formats are not compatible.(Thanks Greg & Ray!)- This is theversion of digital modulation Yaesu chose for their new 'SystemFusion' amateurradios. This is an FDMA signal format using the AMBE+ codec & is notcompatible with C4FM P25 radios.ofthe decoded audio. (Thanks Greg & Bob!)- dPMR is anotheropen-standard digital format created by the ETSI, and is verysimilar to NXDN. It is used almost exclusively in the 6.25KHz mode,and two separate signal streams can occupy the same 12.5KHz spacewithout any interference to each other.

(ThanksPetardete!)Section 4 - Trunked Radio Systems- The title is pretty self-explanatory - This was the 3600 baud datastream used in the first Type-I trunk systems.- This is the current control channel style in use for most modernMotorola Type-I, Type-II, and Type-IIi Hybrid systems. This is a3600 baud data stream, and was sampled from the East Brunswick, NJSmartNet system.- This control channelstream is very similar to the SmartNet stream above, but wasrecorded from the NJ State Police Troop B SmartZone system.

Baofeng P25

I'munsure if the difference in the sound is because the system is aSmartZone, or because of the much larger volume of data beingtransmitted.- In the last few months of 2006, theNJSP completed an upgrade to the statewide trunked radio system.They upgraded the 3 separate SmartZone system in to one seamlessOmniLink setup. Users from any part of the state can now leave theirradios turned to their primary home talkgroup, and the system willfollow them, even if they cross system boundaries.

The upgrade seemsto have added some interesting characteristics to the sound of thedata stream.- Project-25 trunking is a completely digital,vendor-independent specification that was initially developed byMotorola, and now has product offerings & support from Harris, Kenwood, EFJohnson, & others. The original Phase-I systems are deployed as C4FM or CQPSK-LSM (Compatible QuadraturePhase Shift Keying - Linear Simulcast Modulation) if sent at a 12.5KHz spread. If the system is set at the new 6.25 KHz spacing, it isjust known as CQPSK. This is a 9600 baud data stream, and is what aMotorola-built Phase-I (C4FM) system sounds like. This is what a Motorola-built P25system sounds like that is capable of both Phase-I (CQPSK-LSM)and Phase-II (H-DQPSK) audio. This is what a Harris-built P25 Phase-I(C4FM) system sounds like.P25 Test Patterns - These are a pair of datastreams submitted by the same user as the sounds above. Neither wasable to be decoded as a control or voice transmission.

Any help inidentifying what these are is greatly appreciated! -.- This is a sample of the sound that a Motorolatrunk system will make if the site controller has failed, and thechannels are operating in a conventional mode. The static you hearbetween the tones is encrypted analog voice. Here is anof aType-II SmartNet system when operating in this condition.(Thanks Greg & Matt!)- This is the most common form of control channel used in EDACSsystems. This is a 9600 baud data stream.

When the system is passingvoice traffic, you can actually hear the rhythm of the data change.- This is a very seldom seen variant of the standard EDACS system.Here in NJ, Verona Twp. On UHF and Trump Plaza Casino on 900 MHz usethis system. This is a 4800 baud data stream.-The actual name for this sound is 'Scrambled Data Calls', and was asystem diagnostic tool to verify on a regular basis that the workingchannel repeater was passing random data correctly.

It wasoriginally designed as an automated test using something other thannormal system data. Once system admins discovered local mediaoutlets complaining about the noise, many used this as an excuse toenable the feature at much more frequent intervals as a deterrent tooutside listeners. (ThanksJim & Mark!)- Thissound was implemented by GE as a way for engineers & techs to beable to confirm the 'Channel Drop Message' had been properly sent bythe radios in the system when monitoring on a standard analogreceiver.

Actual EDACS radios receive the CDM digitally & don't relyon the sound that's heard over the air. (Thanks Greg& Mark!)- This is thelatest technology system to come out of Harris.

This system isbasically a.Every radio has an IP address, and the mobiles can fully supportvoice & data simultaneously (i.e. an officer's MDT). This system utilizes theAMBE vocoder (similar to the ICOM D-STAR system), and transmits overa 4:1 TDMA broadcast format. The fundamental design of this systemis completely different compared to a Motorola or EDACS system -They use their control channel to tell units on the system to switchto different voice frequencies for reception of radio traffic.OpenSky sends the voice component back over the same stream thatcarries the control data.

This sample came from the Pennsylvaniastate-wide system. There is currently no form of receiver that candecode this system. Thanks to an anonymous user, we now havean of what the format sounds like to the end-user (via a HarrisM7200 mobile radio)!- This is an unknown data stream copied off the NJTurnpike Authority 220 MHz Passport system. If anyone knows what isbeing sent in these (possibly GPS location data?), please let meknow.

(Thanks Greg!)- Sounding somewhat similar to aMotorola Type-II 3600-baud control channel, the tempo of the controlchannel actually changes as users are talking on the voice channels.(Thanks Nick!)- MotoTRBO CapacityPlus trunking systems broadcast thisevery 2 seconds to keep subscriber radios updated & synced to thesystem. (Thanks Nick!)- This is the control channel used by Kenwood's version of NXDN inthe 4800 baud (6.25k) trunking format. This trunking mode is incompatible with the Icom IDAS NXDN radios (they have their own version of trunkingcalled MULTITRUNK).

(Thanks Nick!)- This is the control channel used by KenwoodNEXEDGE NXDN trunking when operating in the 9600 baud (12.5k)format. (Thanks Jacob!)-This is a highly successful trunking radio network design usedoutside the USA in many European, Asian, & South American countries.It is a 4:1 TDMA system that is primarily deployed at 380MHz andabove. A well-written description of thesystem can be found, and anis now available of what it sounds like to the end-user (DMO mode -non-repeated). The NJ Transit corporation has won approvalto deploy a TETRA system here in the U.S. To replace their agingMotorola Type-IIi trunk systems using their existing 800MHz licenses.The infrastructure is now on-air, and data streamthen the European version. ( ThanksRoland & Greg!)- This is the secondmost popular trunking format in Europe for those that choose not todeploy TETRA systems. These systems are primarily used by police ormilitary organizations.

It is a narrowband format FDMA signal usingGMSK modulation. The systems employ strong end-to-end encryption bedefault, and cannot be monitored by scanners or receivers. This is a sample of thevoice signal 'in the raw'.(Thanks Martin!)- Thisis a trunking protocol that is very popular in the UK.

There areveryfew systems here in US that use this ( Decatur, TX andDouglas County, WA ).There is currently no form of receiver that can decode this system.-I figured I'd add this here because the iDEN networks used byNEXTEL, Telus, SouthernLinc, etc. Are a derivative of Motorola'solder VSELP digital trunking transmitted over a standard 6:1 TDMAcell format. This is what it sounds like in the raw.- The NJSP system used to use this model of receiver with a 'voting'comparator to mange incoming signals from the multiple receive sitesconnected to the controller. Since the remote links are never turnedoff, and always transmitting, they send a 2175 Hz. Tone when notbroadcasting audio. What you are hearing here is the split-seconddelay between the Trooper ending his transmission, and thecomparator realizing that it needs to switch off broadcasting thatreceiver.

(Thanks Steve! )- This is the sound a user's radio makes when the requestto transmit on a trunk system has been granted by the sitecontroller. ( Thanks Matt!)- This is the sound Motorola MotoTRBO DMR radios make whentransmitting 'in the clear' on both conventional & trunked channels.( Thanks Dave!)- This is the sound Motorola MotoTRBO DMR radiosmake when transmitting in 'secure' mode on both conventional &trunked channels. ( Thanks Dave!)- This is the sound that a modern Harris radio will makewhen you are about to reach the TX timeout threshold. ( ThanksFernando!).

Encryption in radio communications enables secure communication between parties and is achieved by loading the same key into all radios in a group.The key is like a secret number or password that must be known in order to decrypt the call. Radios in their group can then talk amongst each other privately, and no outsiders can intercept the communications. Although analog encryption is possible, this typically degrades the audio quality and also results in a reduced coverage area, as stronger RF signals are needed to clearly receive the encrypted calls.One of the key benefits of P25 Digital Radio over analog radio is the ability to securely encrypt calls without impacting the coverage area.Enabling P25 encryption is easy. A channel or group is programmed to use encryption and a key is loaded into each radio that uses that group.DES uses a 56-bit encryption key and AES uses a 256-bit encryption key. The type of encryption to use depends on the type of information you’re protecting.AES is a more secure form of encryption, however maintaining the security of that channel is more complicated.Policies and procedures will need to be put into place to determine who is allowed to access the secure channel. In addition, plans will need to be in place to determine what to do if a radio with the key is lost or stolen.

Often this is easily managed by having more than one encryption key.Tactical teams that require a higher level of security may generate their own encryption keys for specific operations. They can tightly control or manage those radios, and have an up to date knowledge of their current status. A different key is used to encrypt general day-to-day communications and is available to a wide group of people.Because a large group of people have access to this channel and the key, it is considered to have a low-level security. If the radio is lost, it could take some time for this to be reported and disabled. And replacing the key and all of the radios will be a time consuming, costly exercise and may only happen on rare occasions.Larger systems may use a feature called over the air rekeying, or OTAR. This allows the updating of the key over the air and dramatically simplifies the process of rekeying the radios in the field. You do not need to physically touch each radio to load the key with a key-loader.

However, OTAR still has an administration overhead to track down and follow-up on any problem radios that could not be rekeyed. This is common where multiple shifts, spare radios, and specialist vehicles mean radios are not powered on and active on the radio system all of the time.In summary, P25 makes it very easy to add encryption to a radio system. However, it is important to have a good plan in place to ensure communication stays secure and the administrative overhead of managing the radios is in line with the level of security required.This concludes our introduction to P25. We hope it was helpful for you.If you’d like to contact us please follow the link below or post in the.