Understanding the technical stuff in a two-way radio datasheet.



Motorola Solutions produces (detailed) datasheets for all radio devices. On the last page, there is a table with all kinds of technical data that is of interest to techie-folk like me, but will be meaningless to anyone else. In this post I will attempt to explain what all of these technical terms mean in simple terms so that everyone can understand them.


Frequency Range (Band)

All MOTOTRBO radios operate on one frequency band. This might be VHF or UHF. In some cases, the choice might be governed by an existing spectrum licence or whatever frequencies the regulator is able to offer you. In rare cases you might be able to choose.

UHF (which is usually 400-520MHz) tends to work better indoors or in a dense urban area. VHF tends to work better in rural and suburban areas.

In some parts of the world, you might be able to get radios that operate on the 300MHz VHF band or 800MHz UHF band. If the latter is available to you, this would be the best choice for indoor coverage.


Power Output

A two way radio consists of a transmitter and receiver. The transmitter emits a signal when the PTT is pressed. The level of this outgoing signal is quite high since it must travel some distance to the repeater or whoever is listening.

The level of this signal is stated in Watts (W). Generally, the higher the power, the further the signal will go.

UHF (400MHz) portable radios usually put out 4W whereas VHF radios do 5W. Mobile (vehicle mounted) radios generally either come as a 25W or 45W variant.

The difference in transmit power has to do with safety. The assumption is that a portable radio would be held close to the body whereas a mobile would use a vehicle antenna, some distance from the user.

ATEX intrinsically safe portable radios will only do 1W on both UHF or VHF.

In practice, there is no noticable difference between 4W and 5W when it comes to range. When a portable radio transmit at full (4/5W) power, it will comsume more battery power. Therefore it is possible to configure the radio to allow the user to switch between low and high power depending on what is needed at that time.


Channel Spacing

The above frequency bands are shared between different users by means of physical channels. These physical channels are seperated by a few kilohertz (kHz) so that the licencees on adjacent frequencies do not interfere with each other. The amount of seperate between physical frequenices varies in different parts of the world but where I work, this is generally 12,5kHz.

Radio systems that use DMR will automatically use 12,5kHz channel spacing but it is not neccesary to configure the radio onto frequencies that are a multiple of 12,5kHz.

Analogue radio systems can use any channel spacing, depending on what the telecommunications regulator requires but generally these will also be 12,5kHz. But if the regulator requires 20kHz or 25kHz, most radios will be able to support this.

The channel spacing is changed using CPS programming software (or Radio Management). Changing this setting tells the radio to use a different bandwidth for the IF filter and a different FM devaition level - bothare applicable to analogue channels only. For DMR (digital) channels, the channel spacing is always 12,5kHz.

Setting the radio to 12,5kHz when it will be used on a 25kHz channel will make the user seem soft when transmitting and all incoming transmissions when receiveing will seem to be distorted.

Setting the radio to 25kHz channel spacing when it will be used on a 12,5kHz channel will have the opposite effect. The user will sound distorted when transmitting and all incoming transmissions when receiveing will sound soft.

Channel Capacity

This tells you how many channels can be programmed into a radio. Even though a DMR radio system may not have hundreds of physical channels, it will have many talkgroups. Having many channels allows system operators to program radios in such a way that allows a user to switch between talkgroups using their channel selector switch.

So for example, radio X could be programmed as follows:


In this case, changing between channel 1, 2, 3 and 4 does not change the transmit and recieve frequencies but it does change the talkgroup used. For the user it will appear that they have "changed channels" but inreality they have just switched between talkgroups.


Battery Life

This specification is only applicable to portable radios. It shows how long a user could expect the battery to last for a given useage profile. 
The useage profile is sort of an industry standard: 90/5/5 - meaning 90% of the time, the rsadio is idle; 5% it will transmit and 5% of the time, it will receive at a normal volume. GNSS; bluetooth and any other superflous features are assumed to be off.

If a user uses their radio more (i.e. it is less than 90% idle) then the battery discharge time will decrease. In some cases, the radio will transmit without the users intervention or knowledge (e.g. sends a location update or registers at another site) which will make the battery run flat quicker and the user may think that there is a fault with their radio.

In the early days of MOTOTRBO, there were quite a few cases where customers had set up GPS in the fielded radios but did not deploy a location tracking solution. The result was that radios would flood the system with registrations and location updates. As a result, the channel was always busy but nobodxy was speaking and all portable radios has flat batteries within a few hours since they were constantlly transmitting and evener went into battery saver mode.

Portable radios have a battery saver mode that reduces current drain when there is no activity on the channel and the user is not doing anything.


Operating Temperature

This is the temperature range in which the radio will operate normally. The product specifications will also not very drastically.

Note that this applies mostly to the radio unit itself. Rechargable batteries for example will not provide full capacity when they are subjected to very low or very high temperatures.

Radios are tested during the design phase, to confirm that they are able to perform normally at temperature extremes, as part of the ALT and MIL-STD 810 certification (see below).


Modulation

All LMR equipment will support FM (Frequency Modulation) when operating in analogue mode. MOTOTRBO equipment operating in digital mode will use 4FSK modulation.

To avoid confusion, most manufacturers will also list the ITU code for the above. For example, in analogue mode, a LMR two-way radio will most likely use 11K2F3E. This number is important as it might be needed when completing a spectrum licence appliucation. 11K2F3E tells the telecommunications regulator that the equipment in question will use FM; carry voice and use 11,2kHz bandwidth (which equates to the bandwidth needed to put an FM signal on a 12,5kHz radio channel (see channel spacing).

On a MOTOTRBO radio that will use voice and data, the code will be 7K60F1W. This tells the regulator that the radio equipment will use Digital FM; carry voice and all kinds of data and will use 7,6kHz bandwidth - which fits nicely into a 12,5kHz channel. 
The reason for the F in 7K60F1W is that 4FSK modaultion is a form of frequency modulation but becuase the voice is sent digitally there is a 1 after the F.

For more information on ITU codes, have a look at Wikipedia.

Digital Protocol

On DMR radios, this will always be ETSI TS 102-361 and AMBE+2. The former is the technical specification that defines how DMR should work and the latter is the vocoder all manufactuerers have agreed to use. If the equipment does not list both, the device might not work with other DMR radios.

Conducted and Radiated Emmision

Conducted and radiated emissions are terms used to describe the electromagnetic energy that is unintentionally emitted by electronic devices.

Conducted emissions refer to the electromagnetic energy that is conducted through power cords microphone cables etc. These emissions can occur due to the switching of electronic components, high-frequency signals, or other electrical disturbances within a radio. Conducted emissions can potentially interfere with other devices connected to the same power source or the radio itself.

Radiated emissions refer to the electromagnetic energy that is radiated or emitted into the surrounding environment by the radio. These emissions may be emmited from the antenna; connectors or other components that could act as unintentional antennas. Excessive radiated emissions can cause electromagnetic interference with other nearby electronic devices or radio equipment.

In order for a two-way radio to marketed in, for example the EU, it has to comply a number of standards refferrred to in the EU Radio Equipment Directive 2014/53/EU. The standards a radio complies with are listed on the Declaration of Conformity.


Adjacent Channel Power

Adjacent Channel Power refers to the power level of a signal from a transmitting two-way radio that spills over into the adjacent channels (i.e. 12,5kHz above and below). This spillover can potentially degrade the performance of other radio systems operating on adjacent frequecies.

Adjacent Channel Power is usually specified as a ratio, relative to the total power of the signal, in decibels (dB). For example, an Adjacent Channel Power of -60 dB means that the power in the adjacent channels is 60 dB lower than the total power of the transmitted signal. A lower Adjacent Channel Power value indicates better design and reduced interference to neighboring channels.


Frequency Stability

This specification tells how much the transmit and receive frequency will vary under normal working conditions. MOTOTRBO radios will almost always have a frequency stability of 0,5ppm (parts per million).

The lowe this value, the more care was put into the design of the radio. I've seen CCC radios with a frequency stability of 1ppm (on paper) and worse (when tested).

The transmit frequency of a radio, with a frequency stability of 0,5ppm and operating on 150MHz, will not go above 150,00075MHz or below 149,999925MHz. Although this does not seem that much, at 400 and 800MHz having a good frequency stability becomes important.


Sensitivity

For MOTOTRBO radios, two values are given: one for analogue and one for digital. For the analogue specification, a value in microvolts (µV) is given at 12dB SINAD.

SINAD is an acronym for SIgnal; Noise And Distortion. It is basically a measurement of the signal to noise ratio. A strong signal will have a very high signal to noise ratio whereas a weak signal will have a low signal to noise ratio. 12dB is an industry standard measurement point since it represents the weakest possible signal that will produce good readability. 12dB SINAD means that the signal to noise ratio (including any distortion) is 12 decibels (dB).

The decibel is a logarithmic measurement which means that the signal to noise ratio is, in this case, around 4:1. (1: 3,9811 if you want to be accurate).


Intermodulation Rejection

Intermodulation rejection refers to a measure of how well a radio can reject or minimize unwanted intermodulation products. Intermodulation products occur when two or more different signals are combined or mixed in the radio, resulting in additional unwanted signals that were not present in the original input signals.

Intermodulation rejection is expressed as a ratio in decibels (dB). The higher the intermodulation rejection value, the better the rejection of unwanted signals produced by intermodulation products. For example, an ntermodulation rejection rating of 80dB means that the radio is capable of attenuating the intermodulation products by 80 decibels relative to the desired signals - in linear terms, that's a factor of 10.000.

Intermodulation rejection is especially critical in applications such as wireless communication systems, where multiple signals of different frequencies are combined and transmitted simultaneously. If the intermodulation rejection is low, the intermodulation products can interfere with the desired signals, degrading the overall system performance and causing interference.

To achieve high intermodulation rejection, designers employ various techniques such as using linear and low-distortion components, employing effective filtering methods, and ensuring proper signal isolation. These measures help reduce the nonlinearities in the system and minimize the generation of intermodulation products, thereby improving the overall performance and signal quality.


Adjacent Channel Selectivity

Adjacent Channel Selectivity refers to the ability of a radio receiver to reject or minimize interference from signals transmitted on adjacent channels (12,5kHz above and below). 

Adjacent Channel Selectivity becomes important in installations where there are multiple transmitters operating in close proximity, such as in densely populated urban areas or within a shared frequency band. The goal is to ensure that the radios' receiver can effectively receive signals from its intended channel while rejecting or minimizing interference from neighboring channels.

When a receiver has good adjacent channel selectivity, it can discriminate between the desired signal in its assigned channel and signals in adjacent channels that may leak into the receiver's passband. 


Audio Response

This shows what the audio response is like. All two way radios will have the same audio response curve since this is standardised in TIA 603 and other standards.

All two-way radios will only pass a specific part of audible frequencies neccesary for voice communications over a regular 12,5kHz LMR radio channel. This is essentially between 300Hz and 3kHz.
Audio frequneies below 300Hz are filtred out as this is used by PL and DPL on analogue systems. In any case, there is not much intellugibe speech below 300Hz (unless you've have a voice like Barry White or Frank Mullen and want to impress somebody on the radio).
Audio frequencies above 3kHz are also filtred out as these are not needed for voice - or at least this is the minimum bandwidth needed to pass clear audio.

Audio Power Output 

This is how many watts the audio amplifier can produce and is measured in watts. A higher audio output power does not neccesarily equate to a louder radio since this is also reliant on the speaker and radio/speaker cabinet design. 

Loudness

Loudness is probably more important than audio output power since this is what the radio user will experience. The unit of measurement is dB Phon which is the measurement for percived loudness.

Digital Vocoder

For DMR radios this will always be AMBE+2.

Hum and Noise

Hum and Noise refers to unwanted disturbances or signals that can degrade the quality of the received or tansmitted signal. It is only used in relation to analogue (FM) radio systems but can also affact equipment that operates in digital mode. It is most noticeable when transmitting.

Hum would be low-frequency noise typically caused by; mechainical problems; electrical interference or ground loops. It often manifests as a steady, low-pitched sound or vibration.
Noise would typically be generated by the components themselves or the combined circuitry.

Both hum and noise can negatively impact the quality of radio communications, making it harder to understand the transmitted information.

It is represented as a ratio of the deviation, produced by a 100% modulated and unmodulated transmission, in decibels (dB). Typically one should expect to see a hum and noise ratio of 40dB or higher.

MIL-STD 810

MIL-STD-810 is a US Military Standard that defines a series of environmental tests, that simulate what a piece of equipment would need to endure during its its service life. Although the standard was  originally prepared for the US Military, it is often used for non-military equipment and has become a de-facto standard across the radio communications industry.

Essentially, a piece of equipment that has undergone MIL-STD-810 testing should be able to withstand a number of environmental extremes such as heat; cold; dust; salt fog; vibration and drop testing. 
  

IP Rating

All devices that are intended for industrial use, will have undergone IP testing. In this case, IP originates from the French term Indice de Protection and is defined in EN 60529. This rating classifies and rates the degree of protection, provided by the devices casing, against dust and water.

All Motorola equipment has undergone EN 60529 testing and will have a IP rating listed on the specification sheet. A radio that has a higher IP rating will be more resistant to dust and water and therefore would be better suited for ship communications; water police; mining; construction and so forth.

For more details, see this post.


Other Stuff

On radios like the R7, the datasheet will also mention the Wi-Fi; Bluetooth and GNSS specifications:

Wi-Fi Frequency Ranges

There are essentially two frequency ranges availavle for Wi-Fi: 2,4 and 5GHz. A radio which supports both is better since 2,4GHz can get congested.

Wi-Fi Standards Supported

Wi-Fi is defined by IEEE 802.11. There have been several revisions to this standard and so a radio will list these. For example, the R7 supports revisions a; b; g; n and ac of the IEEE 802.11 standard.

Not all radios have Wi-Fi functionality and not all will support 5GHz.

To find out what Wi-Fi in a two-way radio can do for you, see here.

Security Protocol Supported

As a minimum, a two-way radio with Wi-Fi functionality should support WPA-2. The R7 forexample, also supports WPA-3. All MOTOTRBO radios will support 802.1x certificate-based access.
All of these are security mechainsms needed to protect private Wi-Fi networks (i.e. networks that require you to have a passcode to access them).

Wi-Fi Protected Access 2 (WPA2), and Wi-Fi Protected Access 3 (WPA3) are the three security certification programs created by the Wi-Fi Alliance (an industry body) to secure WPA was created in response to serious weaknesses researchers had found in Wired Equivalent Privacy (WEP).

To find out what Wi-Fi in a two-way radio can do for you, see here.


Maximum Number of SSIDs

This tells how many SSIDs (Service Set IDentifier) the radio can store. Each Wi-Fi network will have a unique SSID. The SSID is the name that can (but is not always) be shown when looking for Wi-Fi networks on your phone or computer.

To find out what Wi-Fi in a two-way radio can do for you, see here.
 

GNSS Constellation Support

There are a number of GNSS (Global Navigation Satellite System) around today. The most widely used and commonly known is GPS. There is also GLONASS and Beidu. In Europe we also have Galileo.

GNSS is two way radios allow the system operator to monitor the location of radio users. This helps them be more efficient and keeps personell safe.


GNSS Time To First Fix

This is a measurement of how fast the radio can get a location fix. There are usually two values given: cold start for when the radio switches on and warm start where the radio was on but did not have any signal before (e.g. the radio user was in the basement when they switched on and then walked/drove outside).


GNSS Horizontal Accuracy

This specifications states how accurate the location fix will be in ideal circumstances. It is related to the geometric dillution of precision. See here for more details.


Bluetooth Version

This is the version of Bluetooth the radio supports. Ideally it should be version 5 or higher but version 4 is okay. A radio which supports Bluetooth version 5 will be able to work with peripherals which support version 4 or lower.

Bluetooth Range/Class

As the name suggests, this tells you how far away one could get from the radio with an accessory in ideal circumstances. Having a range of say 10m is not a garantee that you'll always get ten meters.

A better option, in my opinion, would be to list the Bluetooth class. This indicates how much RF wpoer the Bluetooth transciver in the radio can emit and will give someone with RF knowledge an idea of what to expect.

Bluetooth Profiles/Services

This lists what services the Bluetooth transciver in the radio will support. In essence it telly you what kind of peripherals you can connect to the radio. For example, in addition to all the other services, MOTORBO radios such as the R7 support GATT which allows them to be integrated with biometric sensors like this.



Did I miss something? If I did miss something or you have further questions about any of these points, leave a comment below.
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