03-15.1 Airwave Training_870e938acca029cccd0ba4166c213177.pdf

OFFICIAL Unit 3 Lesson 15.1...

OFFICIAL Unit 3 Lesson 15.1 Airwave Training Lesson Aim: The learner will be able to operate selected functions of the handheld Airwave terminals Learning Outcomes: On successful completion of the lesson, Introduction students will be able to:- “Airwave” is the name given to the communication system that Police Scotland 1. State the advantages to the Airwave use. The system is a national, digital radio communication system (pg. 2) communication service that uses up to date technology. 2. Understand the functions of the Airwave You will be provided a personal issue terminal in relation to: (pg. 3-18) handheld Airwave terminal that connects to Talkgroups this system when you are deployed operationally. Primary Talkgroups The Airwave system services all the Trunked Mode Operation emergency services across the United Direct Mode Operation Kingdom, including the Police Forces in England and Wales, the Scottish Fire and Emergency Button Rescue Service (SFRS) and the Scottish Point to Point Ambulance Services (SAS). Transmit inhibit Police Scotland use the Motorola MTH 800 as depicted in this note and the MTP 6650. Telephone Calls and Text messaging The system allows use of both handheld and vehicle mounted units. British Transport Police have adopted the Sepura terminal which is similar in design and operation to the Motorola unit. 1 th Amended 24 April 2024 v.4 OFFICIAL  OFFICIAL Unit 3 Lesson 15.1 Airwave Training This lesson is intended to familiarise you with the functions of the handheld terminal. You will have opportunities throughout your Initial Training Course to practice certain functions, particularly in respect of radio communication. The different features of the Airwave system provide a very flexible communications system, allowing integration between emergency services as well as dedicated communications which do not interfere with day to day radio traffic. The Advantages of the Airwave Radio System The Airwave system will allow the use of handheld terminals as well as vehicle-based units. The service provides a communications system that is both secure and effective, the main benefits being:- Improved Officer Safety The system can provide Automatic Vehicle Location, Automatic Personnel Location and has an emergency button. Operation of the emergency button cuts out all other radio traffic and switches on the microphone of the terminal, allowing the officer to make an emergency call, for example to summon urgent assistance. Clarity of Radio Voice Transmissions Voice transmission and reception over a digital network is extremely clear with background noise on voice communication being filtered out. Secure, Encrypted Communications for All Users Encrypted radio transmissions cannot be detected by the use of scanning devices. Therefore, all Airwave radios will have a high level of encryption thereby offering a very secure radio service. Extended Coverage There are many base stations throughout the UK providing network coverage. It will be possible to use the continuous nature of the coverage available to contact officers on a force, regional or national basis. Opportunity to integrate other functionality, such as telephony and data Airwave will allow transmission of various forms of data. The terminal can be used as a network radio, a ‘point to point’ radio between individual terminals, a mobile telephone, and a data or text receiver. Computer data can be carried on the network and in the future, it could be possible to include fingerprint recognition, video pictures or fax data. 2 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 15.1 Airwave Training Professional Standards PS Please be aware that ALL forms of use of an Airwave terminal are monitored and recorded. Legitimate use of the terminals is obviously allowed and encouraged. However, inappropriate use such as excessive use of the point to point feature, or making non-essential telephone calls or text messages, could result in disciplinary action being taken against you. Operational Use When you are deployed operationally you should seek local guidance on the following:- The personal issue of the Airwave terminal to you and its registration with the Area Control Room (ACR). The storage and recharging of terminals. The security of the terminal within the station and, if applicable, your home. However, lost or stolen terminals can be remotely activated or rendered inoperative to prevent criminal use. The action to be taken in respect of reporting that a terminal has been lost, stolen or damaged. The safe storage and security required in respect of Airwave Terminals cannot be over-emphasised. You will learn in the following pages that Terminals can be used to access police communications in a variety of methods and over a far greater range than was previously available. Criminal use of terminals and access to the Airwave system would be disastrous and destroy all of the advantages of the system. For this reason, the loss or theft of a terminal must be reported immediately. Prompt action can then be taken to remotely destroy the terminal’s operating capacity, rendering it functionally useless. 3 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 15.1 Airwave Training Methods of Communication Using Airwave The Airwave terminal itself resembles a large mobile telephone, a device with which many will be very familiar in terms of voice and text transmission, with the addition of several features with which you might not be so comfortable. We will concentrate on these new items, providing you with an overview of them. Later, you will be given many opportunities for practice with the radios during practical scenarios. The use of the terminal for telephone and text functions will be the subject of further training when you take up operational duties. The terms associated with radio functions of the Airwave terminal are:- 1. Talkgroups 2. Primary Talkgroups 3. Trunked Mode Operation 4. Direct Mode Operation 5. Emergency Button 6. Point to Point 7. Transmit inhibit 8. Telephone Calls and Text messaging Setting up the Airwave Terminal The first points to be aware of are:- Attaching and detaching the battery from the terminal Powering up and powering off the terminal Recognising the network connection tone Identifying the LED & recognising LCD Symbols Checking battery levels Locking and unlocking the keypad The resemblance of an Airwave terminal to an ordinary mobile telephone might tempt some to try inserting their own SIM cards into the terminal. This should be avoided at all costs since this action will simply destroy the SIM card, rendering it useless when replaced in the original mobile telephone. 4 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 15.1 Airwave Training Features of the Motorola MTH800 Terminal Emergency Button LED Indicator of radio status. Earpiece Top Microphone Hold to your ear to listen to phone calls Speak into this during radio and point-to-point calls. communications. Press to Talk (PTT) Key Colour Display Press and hold to talk. Release to listen. Menu Key On/Off/End/Home Key Use this to turn the MTH800 on/off. Loud/Discreet Mode Key Bottom Microphone Use to switch between loud/discreet Speak into this during telephone mode and to activate/deactivate communications. speakerphone. Adjacent to the Emergency button is an LED which indicates the level of activation of the terminal as shown in the diagram below. These indications are important. The majority of the time the steady green light will provide reassurance that the device is in service. However, a steady red light will warn that there is no service, and a steady amber light will warn that you cannot transmit (see ‘Transmit Inhibit’ later in these notes) Emergency Button Press and hold to initiate emergency mode. Antenna Volume Rotator To lock, press and hold until confirmation tone. 3 Colour LED In Use (Flashing) Reception No Reception (Flashing) Connecting to network Transmit Inhibit (TXI) in service Device switched off 5 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 15.1 Airwave Training Features of the Motorola MTP 6650 Terminal There are some other points which it might be useful to note:- Batteries can be recharged as desired. There is no ‘memory’ feature included in the batteries, which means that they do not have to be fully discharged prior to recharging. Arrangements will be made locally for the issue of terminals and chargers, but it will be the responsibility of individual officers to ensure that batteries are charged ready for duty. 6 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 15.1 Airwave Training If you forget to charge the battery of your terminal, you might not have communications during your period of duty. Talkgroups You might be familiar with the term ‘channels’ in the context of radio communication. In respect of Airwave, the term ‘Talkgroup’ is used to describe the channels through which a group of officers will communicate with each other. Each terminal issued to users will contain a range of talkgroups, pre-programmed and configured to facilitate communications over a variety of circumstances. However, talkgroups are selected in much the same way as a channel on the current radio. Example:- A patrol officer working in a town centre would use the talkgroup for that town/sector. At the same time within the town, CID officers engaged on a search warrant could use a separate departmental talkgroup or spare town/sector talkgroup. Primary Talkgroup Officers working in their respective local policing areas will communicate on a primary or ‘home’ talkgroup. The standard mode of operation of the Airwave system is open communication. All terminals will receive all transmissions made on that talkgroup. When an incident occurs, or a pre-planned operation is put into effect, officers concerned may be instructed to change their Airwave terminal to operate on a different, dedicated talkgroup, so that normal day to day operations are not affected. Example:- When you attend an event such as a football match or other large-scale public event you will have access to a talkgroup allocated for that occasion. This will be identified as part of the forward planning for the event. Operationally, other talkgroups for firearms, public order and other specialist areas will be programmed into the officers’ personal issue terminal, in line with their respective roles. Selecting a Talkgroup The menus of the terminal are accessed in much the same way as you would do with a mobile telephone. However, as well as being necessary for telephone functions, menus are also necessary to access radio functions such as talkgroups. 7 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 15.1 Airwave Training Access to the menus is achieved by pressing the ‘menu’ key, and thereafter using menu navigation keys ▲/▼ and following the on- screen instructions. Rather like a computer which stores files in folders, the Airwave Terminal stores sets of relevant ‘talkgroups’ together in ‘folders’. Changing folders is achieved by using the navigation keys and soft keys. To search for a folder, carry out a ‘folder search’:- press “Optns”; select ‘Folder’ then scroll to the required ‘Folder’; press select; or press “Optns”; select ‘TG by Folder’, press select then scroll to the required folder; then press “Select”. It is also possible to carry out an alphabetical search of folders. To do this:- press “Optns”; select ‘TG by abc’, followed by the appropriate letter for the first character of the required Talkgroup. Scroll to the required Talkgroup then press “Select”. Changing a Talkgroup To change talkgroups, either:- Press the navigation button to the left or the right; or Press ‘Optns’ and use the navigation button to scroll to the relevant folder. Press ‘select’ to move to the appropriate talkgroup. This might all seem a little complex at first, but with practice changing talkgroups will become second nature to you. Changing talkgroups is an essential and everyday part of the operation of the Airwave terminal. 8 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 15.1 Airwave Training Trunked Mode Operation (TMO) Trunked Mode operation is commonly called TMO. This is the normal mode by which communications are conducted across all talkgroups. The mode is encrypted, utilises the main Airwave Service network, and cannot be intercepted by scanner or other devices. Although Airwave provides a communication system which represents a massive improvement on previous systems, there are limitations. Coverage can be restricted, particularly within buildings which have thick stone walls or in some new buildings. The drive to provide energy efficiency can produce a building which effectively shields an Airwave terminal from incoming and outgoing signals. In an operational setting, there will be local knowledge of such issues and local arrangements will be in place to cope with such constraints. When in TMO, the terminal can be used for:- Radio Calls Point-to-Point mode Phone mode Emergency Button Status Updates Text Messaging A TMO Radio Call involves:- ALL members of a talkgroup It can be expanded to include more than one talkgroup It includes a dispatcher or controller Only the dispatcher can talk over anyone else who is transmitting on the same talkgroup Calls are transmitted and received as per normal radio operations, i.e. press the PTT (Press to Talk) button to talk, release the PTT button to listen 9 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 15.1 Airwave Training To Make a Radio Call Ensure that the correct talkgroup is selected Press the ‘Press to Talk’ button, but wait for a tone - known as the grant tone - to be heard. This tone signifies that the system is ready to accept your message. If you speak before this tone is heard, the first few words of your message will not be transmitted Ensure that you use the correct call sign and radio procedure (this will covered in the Airwave Speak lesson) Release the Press to Talk button to listen to any reply to your message. It is vital that you do not listen in to other talk groups without good reason, or change talkgroups without informing your dispatcher or controller. It is very easy to forget to change back to your assigned talkgroup, making it very difficult for you to be readily contacted when you are needed, or for you to contact control if you need assistance. An example would be if you crossed borders into another division on enquiry. The correct procedure for this type of situation is that one officer would change to this Divisions talkgroup ensuring they contact the relevant control room for officer safety and the other officer remains on the local division. Another characteristic of Airwave is the inability to talk over any ongoing transmission being made by another officer. Anyone wishing to transmit a message will have to wait for other transmissions to end before attempting to communicate. Direct Mode Operation There may be occasions when it will be necessary for you to switch your Airwave terminal from the normal Trunked Mode Operation (TMO) to a mode known as Direct Mode Operation (DMO). This might become necessary because:- You are out of the area of Airwave coverage There is a total system failure - however unlikely this eventuality might be You attend an incident in an area known for poor radio reception. All officers might be instructed to switch to DMO 10 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 15.1 Airwave Training As we saw earlier, when Terminals are operating in Trunked Mode (TMO), terminals are transmitting to the main Airwave system and the signals are amplified and relayed from transmitter to transmitter. However, in Direct Mode Operation (DMO), the Airwave terminal is transmitting directly to another Airwave terminal. For this reason, the range of operation is quite limited and is usually limited to ‘line of sight’. Obstructions between terminals such as buildings or trees, and excessive distance will cause the signal to fail. There is also no encryption, therefore messages could be heard by others with the right equipment. It must also be remembered that:- In Direct Mode Operation (DMO) a terminal is working outside of the network It can only be used to speak to another terminal on the same DMO talkgroup The Emergency Button CAN be activated but it will only be heard by other terminals operating on the same DMO talkgroup The following functions are NOT available in DMO:- Trunked Mode Operation transmissions Phone calls Point-to-Point calls Text messages Remember:- DMO is NOT encrypted. Emergency Button One very important safety device is the emergency button, which all terminals are fitted with. If you are in imminent danger of being injured or attacked, pressing the emergency button will automatically initiate alarms in the control room and on the terminals of other officers on the same talkgroup. On activation of the emergency button, the microphone will become live, allowing speech to be detected from several metres away. This means that if you are forced to drop your terminal or cannot reach the press to talk button, you will still be able to verbally communicate your position or status to other officers and the control room. 11 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 15.1 Airwave Training Using the Emergency Button To operate the emergency button:- Press and hold the Emergency Button for 1.5 seconds This will provide a ‘Hot Mic’. For a period of ten seconds you will have a direct, hands free radio link to your control room and to every other terminal operating on your talkgroup, so that you can summon assistance for yourself or others The Control Room can also open the microphone on a terminal remotely, thereby enhancing officer safety Operation of the Emergency Button When the Emergency Button is in operation:- It cuts out any other transmission from any other terminal in the talkgroup (including those on point-to-point, telephone or text messages) allows you to transmit your location and the nature of the emergency. When the emergency is over:- cancel the activation by pressing ‘END’ and holding ‘EXIT’ until the screen of the terminal clears. The Emergency Button works even when the terminal is switched OFF. It is therefore vital that the Emergency Button is activated only in emergencies. The activation of an Emergency Button by another user would have the following effect on your terminal:- An emergency icon will be displayed There will be an audible alert The identity of the Activator, the person making the emergency call-will be displayed The words ‘Emergency in use’ will be displayed The operation of the Emergency Button effectively overrides any functions which are being conducted by other terminal users within the talkgroup. If you were making a point-to-point call, a telephone 12 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 15.1 Airwave Training call or a text message, these would be cut off by an emergency activation by someone in the same talkgroup. However, if you change talkgroup for any reason, you will miss an emergency call made on your home talkgroup. The Individual Short Subscriber Identifier (ISSI) Every Airwave terminal has a unique Individual Short Subscriber Identifier- commonly known as an ‘ISSI’ - assigned to it. It is important that you are aware of the ISSI assigned to your terminal, since your colleagues will be able to contact you directly (using point to point) by using this number:- MTP 6650 terminal Press ‘Menu’ Scroll to ‘My Info’ and press ‘Select’ Select My ISSI Number The number shown is your ISSI MTH 800 terminal Press ‘Menu’ Scroll to ‘More’ and press ‘Select’ Scroll to ‘My Info’ and press ‘Select’ Select ‘My Private Number’ The number shown is your ISSI 13 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 15.1 Airwave Training Point to Point A Point-to-Point Call is a method of making what is in effect a private radio call to a colleague by using their ISSI number. The terminal is used as a radio, you must press the button to talk and release the button to listen, but the disadvantage is that whilst the terminal is operating in this mode it will NOT receive normal TMO radio messages. Point-to-point calls must be kept short. The only exception to this is if someone operates their Emergency Button, which will cancel the point-to-point call. To make a Point-to-Point call:- Dial the ISSI of the terminal required Press the ‘PTT’ button and release it to make the call Use the correct radio procedure during the call Remember to Press-to-Talk and Release-to-Listen End call by pressing the ‘red phone’ button To accept a Point-to-Point call:- When the ringing tone is heard Note what is said on the screen display Respond within a specified time limit by pressing the ‘PTT’ button Use the correct radio procedure during the call Remember to Press-to-Talk and Release-to-Listen End call with “red phone” You can contact any other officer on any talkgroup by making a point to point call, using the ISSI number of the officer concerned. Transmit Inhibit (TXI) There is evidence to suggest that the operation of a radio or a telephone device within close proximity to certain equipment can have a detrimental effect on the operation of that equipment. You might have seen notices in hospitals and surgeries requesting that people carrying mobile telephones switch them off whilst they are in the building. 14 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 15.1 Airwave Training A valuable feature of the Motorola terminal is Transmit Inhibit, commonly referred to as TXI. This feature will allow your terminal to receive messages, but will not allow you to transmit, thus allowing you to remain contactable without you being able to transmit, thus removing any source of possible danger in this respect. You should activate this feature when you are in or near:- Hospitals or Ambulances Chemical spillages or suspected Improvised Explosive Devices (IEDs) Enforcement devices e.g. Handheld radar devices and breath testing equipment. failure to comply with this instruction can cause the unit to produce a false result. Note:- When refuelling a vehicle switch the vehicle and the Airwave Terminal OFF. To activate the Transmit Inhibit feature:- Press and hold “0” Button The words “TXI Activated” appears on the screen There will be a double beep tone The L.E.D. displays a solid amber light Screen display “TXI Mode” and the current Talkgroup To deactivate Transmit Inhibit:- Press and hold “0” Button The words “TXI Deactivated” appears on the screen There will be a double beep tone The L.E.D. displays a flashing green light The screen displays the last Talkgroup that the unit was using Guidance on interference issues will be specified by Local Orders. Note:- It is very important that on every occasion that you activate TXI, you record the fact in your notebook. This will afford you protection in the event that questions are raised regarding your actions. 15 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 15.1 Airwave Training TXI automatically leaves a footprint on the incident you are attached to on STORM. This can be accessed by defence agents for ‘drink drive’ cases. If TXI is not recorded then it could be argued that officers failed to activate it. Lastly, always remember to reactivate your radio in the same area that you activated TXI, to ensure that you return to your home talkgroup. Soft Key Functions In much the same way that mobile telephones have keys programmed to perform specific tasks, the alpha-numeric keys of the Airwave Terminal have pre-programmed soft key functions. Some are listed and illustrated below:-  - Upper Side Key - Urgent Call (MTH 800)  - Lower Side Key - On Duty (MTH 800) - Urgent Call back (MTP 6650) - High/Low audio earpiece (MTP 6650) 1 - At Scene 3 - Flip screen 4 - Available/ On Patrol 5 - Covert Mode 6 - Off Duty 7 - Call Back 8 - Refreshments 9 - TMO to DMO 0 - TXI On/Off Whilst those functions listed above are the subject of a national agreement, some other keys may be programmed to perform different functions. 16 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 15.1 Airwave Training Urgent Call (status code 14) Urgent Call (status code 14) On Duty (status code 1) Flip Screen Select/Option Key Select/Option Key Flip Screen Off Duty At scene Volume Hi/Low Off Duty TX Inhibit On/Off. DMO On/Off At scene TX Inhibit On/Off. DMO On/Off Status Messaging In the illustration, it will be noted that some soft keys are programmed to automatically update your control room with your current status regarding your activities, for example ‘On Duty’, ‘At scene and dealing with incident’, or ‘Available for detail’. The ability to do this saves time and trouble on your part, and allows you to update your control room automatically without the need to take up radio airspace unnecessarily, or occupy yourself or your controller in routine messaging. To send a status message:- Press the “Menu key” Select “Messages” Select “Send Status” Scroll down to appropriate the status Press “Select” or press “PTT” Press “Home” to return to talkgroup Status codes are agreed throughout Scotland, and you will become familiar with them when you take up operational duties. 17 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 15.1 Airwave Training Telephone Calls and Text Messaging Airwave terminals support the use of telephone functions and you will have access via both handheld and vehicle terminals. With this function you will be able to make contact with the internal force telephone network and the majority of external telephone networks. Using Telephony Mode The ability to use the Airwave Terminal in the same way as a mobile telephone is a major benefit to Police communications as it offers convenience and time saving for operational officers. The Airwave Terminal can be used in the same manner as a normal mobile telephone. There is no need to ‘Press-to-Talk’, or to ‘Release-to-Listen’ as in a radio transmission. Using the Terminal, you can:- Make external or internal calls Receive internal calls only You should remember that whilst the Airwave Terminal is in Telephony Mode, it will not receive TMO or other transmissions. It goes without saying that telephone communication is two-way, in that you can speak and hear the other person at the same time. Effectively, two channels are open at one time, one sending messages and another receiving them. This is in contrast to a radio message when only one channel is open at any one time. For this reason, the telephone function of an Airwave terminal must use sparingly, and only when required operationally. The exact procedure for using the handheld terminal in telephony mode will be explained locally. It should always be remembered that although they will not be routinely monitored, calls will be recorded and audited. Force policy will dictate action to be taken against any officer misusing the facilities extended to them. If an officer within your talkgroup activates their Emergency Button, your telephone call will be automatically terminated and details of the emergency call will be displayed on the screen of your terminal. 18 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 15.1 Airwave Training Text Messaging The Airwave Terminal can be used to send text messages to another terminal in much the same way as you are probably used to doing with your own mobile phone. However, text messages cannot be sent from an Airwave Terminal to a private mobile phone, nor can Airwave Terminals receive such messages. There are several advantages to using text messages, and operational experience will dictate the occasions when this will be the preferable mode of communication. To send a text message:- Press ‘Menu’ and select ‘Messages’ To create a new message, select ‘New Message’ Type in the required message and press ‘send’ Insert the address-ISSI or telephone number-and press ‘send’ To retrieve a text message:- Press ‘Menu’ and select ‘Messages’ Press ‘Inbox’ and a text message status will appear advising you of new and stored messages, e.g. 1 new/0 old Select the required message and select read The Cleartone Terminal Whilst you should always be in possession of your personal issue Airwave Terminal when you are on duty, vehicles will be fitted with a different unit. The Cleartone Lynx CM9000FP Vehicle Fit Terminal will look very different to your personal issue unit, but it will operate on the same Airwave system and will be capable of many of the functions that you will become used to. Training on the use and operation of vehicle fitted units will be done at your local divisions. 19 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 15.1 Airwave Training For further information, use the resources shown below:- Refer to your local guidance in relation to Airwave terminals Review: You can state the advantages to the Airwave communication system You can understand the functions of the Airwave terminal in relation to:- Talkgroups Primary Talkgroups Trunked Mode Operation Direct Mode Operation Emergency Button Point to Point Transmit inhibit Telephone Calls and Text messaging 20 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 15.1 Airwave Training Learning Log: How will what you have learned in this module impact your day-to- day role? Are there any skills or knowledge you would like to develop further following this module? End of Module 21 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 15.1 Airwave Training 22 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL