Identifying Defect Detectors

In the 1980s, CN developed their own overlay talker system for existing Servo installations using the Z80 microprocessor.  Bilingual units were used in Quebec on lines where English-speaking crews would operate.

CSX has developed an in-house talker unit in lieu of utilizing commercially available products like the Progress Rail Micro Talker or the STC iCUBE. These units can be found on Wheel Impact (WILD) detectors and high/wide clearance detectors throughout the CSX system.

The female voice heard on these units is the same as used on their radio-controlled remote switches & radio-activated crossings/warning devices.

Of all of the detector manufacturers, Devtronics models are among the hardest to pin down, particularly on CSX where the first talking detectors extended back to the Seaboard Air Line days.

The 68178, 68278, and MA-1 models all utilized a 9 track tape that used audio tones for timing of words. As the tapes were recorded as the units were replaced, a variety of different voices emerged, and it can be difficult to discern a model solely from the voice. In the examples on the right, you can hear instances in which the same voice is used for all 3 of these models.

The TSA3000 and CMA02 models were newer (compared to the previous 3) hot bearing-capable units. The TSA3000 wasn't a very common model on CSX with only a few dozen, while the CMA02 numbered into the hundreds and lasted much longer.

The UT-1 and later the S.C.A.T. (Supervisory Control Alarm Telemetry) units were not capable of detecting hot bearings, and were thus utilized primarily as dragging equipment or high car detectors.

Ensun was a railroad electronics manufacturer based in Houston, TX specializing in control systems for wayside inspection and locomotive fueling. They manufactured overlay systems for non-talking Servo detectors to give them radio reporting capabilities.

Union Pacific entered into a contract with Ensun for overlay systems in 1984.

In 1986, Ensun was purchased by Harmon Industries.

Harmon has been around for a long time, with many talking defect detector models. However, most of these units share the same two voices, making them all but impossible to differentiate without seeing what's inside the bungalow. Models sharing the same two voices include the Mini Talker II, Model 24, Model 32, Model 46, and Model 75.

One notable variation were Southern Pacific's custom female voices. The first voice (see Southern Pacific #1) was widely used across the system, while the second voice (see Southern Pacific #2) was only heard on the SPCSL line linking Chicago to St. Louis.

The only Harmon unit with a voice unique to itself is the Cyberscan 2000, introduced in the mid 1990s.

The well known voice of Randy Goyer can be heard on MicroHBD & Micro Talker units all across North America. Little has changed with the audio of these units since their debut by Harmon/GE Transportation Systems in the early 2000s, although the units have undergone many internal upgrades. As these units changed ownership several times, and some units are capable of CPU upgrades to bring them up to date, it is better to refer to the unit by what CPU revision it is rather than what company name is printed on the enclosure.

For the trained ear, you may be able to discern early MicroHBDs & Micro Talkers (CPU 1) from more contemporary products (CPU 3). You can hear an ever so slight pauses between the word "track" and the track number, as well as between the letters in "CSX." Additionally, these CPU 1 units say "axles" while CPU 3 units say "axle" (singular).

Norfolk Southern often utilizes Micro Talkers in conjunction with their Stress State Detectors - these are easily identified, as they generally say "NS" instead of "Norfolk Southern" and "MP" instead of "Milepost." However, NS' Micro Talkers used in other roles (such as a dragging equipment detector) use identical speech patterns as their MicroHBD units.

As with previous models, CN has opted to use a custom Canadian male voice for their defect detectors. Note that CN's Sentry 2100s and MicroHBDs share the same voice - see our Canadian National page to learn how to tell them apart.

Servo had a long history of defect detectors, although only the last few models were able to talk as-built: the 9000 & the 9909. The unmistakable voice is often referred to as the "Speak & Spell" model by railfans.

However, things get complicated when looking trying to figure out what's in the bungalow by the voice on the radio. Servo's detectors are modular in nature, and many were retrofitted with talkers after the fact. As far as Servo voices go, Servo introduced a ServoTalk device to give older detectors this functionality.

A notable variation are Canadian Pacific's fleet of System 9000 detectors, which included a custom Canadian male voice. Ontario Northland also utilized the System 9000 with the same custom voice.

Southern Technologies Corp. (STC) has 3 generations of hotbox detectors: the Sentry series, the SmartScan NG, and the SmartScan NG². Non-heat detecting models included certain Sentry models (black casing, whereas heat detecting models had a blue casing), the Small Talk, and the iCUBE.

The Sentry series and the SmartScan NG both use the same voice (that of an STC employee named Paul), which can make it easy to confuse the two. Early Sentry 2058s has a slightly muffled sound, a quicker pace, and the tendency to say "dot" instead of "point" for the milepost location. The Sentry 2058 commonly featured a female voice as well (that of STC employee named Linda), as heard commonly on Southern Pacific and Union Pacific. As of 2024, very few Sentry 2058 units remain in active service, and those that do are exclusively used on shortlines & regionals.

Later Sentry 2100s sound virtually identical to the SmartScan NG, but do have some subtle differences in their pace and the way they say certain numbers. Of note, Canadian National's Sentry 2100s utilize the same voice as their MicroHBD - see our Canadian National page to learn how to tell the difference between the two.

STC's Small Talk was a very simplistic, non-heat detecting unit. NS purchased many of these units to replace its aging ex-Conrail Parker DED 1GG units. They can be identified by their hybrid voice, which utilized the Sentry 2058-style voice for the railroad name & the word "milepost," while the rest of the message utilized the SmartScan NG-style voice. They also say "point" as opposed to "dot" for the milepost location. The Small Talk started production in the 1990s and was replaced by the iCube.

The SmartScan NG was introduced in 2004 as the successor to the Sentry 2100, so knowing which railroads utilized what units and the years they were in service is crucial to knowing what was actually in the bungalow. With that said, the SmartScan NG was a much more widely used model than the Sentry 2100. As of 2024, SmartScan NG units are being replaced en mass with SmartScan NG²s, but there are still a decent number out there.

In lieu of the SmartScan NG, Union Pacific opted to utilize a custom model from STC: the SmartScan IS. The SmartScan IS also utilizes Linda's voice, making it difficult to tell which model a detector is simply by its voice alone.

Additionally, UP had a custom talker manufactured for non-heat sensing capabilities (similar to the Small Talk). This is the Wayside Inspection System, and has the slow pacing similar to the Small Talk while using the same voice heard on UP's Sentry 2058 and SmartScan IS systems.

STC's iCUBE model is a small, non-heat detecting unit used for dragging equipment, slide fences, WILD detectors, etc. (similar in function to Progress Rail's Micro Talker). This model was introduced in the 2010s as a replacement for the Small Talk, and utilized the same voice as the SmartScan NG. Contemporary units use the same computer synthesized voice of the SmartScan NG². Newer UP sites utilize a computer synthesized female voice (named ‘Linda’, but clearly different from the STC employee Linda's voice).

The SmartScan NG² by default has a very distinctive computer-synthesized male voice and began appearing around 2017. Most railroads utilize a voice known as ‘Ryan’, while Canadian Pacific utilizes a bilingual voice known as ‘Matthew.’ Although Union Pacific has opted to use this off-the-shelf unit this time around, these units retain the human voice from the SmartScan IS; albeit with some audible differences. Overall vocabulary pacing is slightly faster compared to the IS, though this changes with phrases like ‘UP Detector, ’M-P-H’, and ‘Detector Out’. These are pieced together with separate words and letters, consistent with the NG²'s default ‘Ryan’ voice. The most obvious spotting feature to identify an NG² in the field is Frauscher transducers, which is the only STC detector powerful enough to use them.

Spirit Solutions was a short-lived manufacturer of thermal imaging-based defect detectors. Only one such installation is known (PT 241.0 on NS' Pittsburgh Line), which was subsequently replaced.

The voice heard here is that of Microsoft Sam, the default voice generator found on Windows 2000 and Windows XP. It is a common voice used by smaller manufacturers, so further verification is needed beyond the voice itself to identify what is actually in the signal bungalow.

Detectors that we have not yet identified. Many are dragging equipment detectors, as they are simpler unit that are easy to build in-house, or were short-lived products from various companies.

• Boston & Maine DED: Older model from at least the early 1990s, if not the 1980s.
• Buckingham Branch DED: Newer model, possibly in-house. It uses the Microsoft Sam voice common to other oddball detectors (such as the Spirit Solutions MidNight Ridir).
• Canadian National DED: No additional information available.
• Reading & Northern DED - Male Voice: Newer model, possibly in-house.
• Reading & Northern DED - Female Voice: Another newer model, again possibly in-house.

Zukinut's ZEPIC-DE dragging equipment detector is a discontinued model. Zukinut does, however, still produce derailment detectors.