NHRC NHRC-2 User manual

NHRC-2 User Guide
NHRC-2 User Guide Page 1 2/28/2000
Copyright © 2000, NHRC LLC
All Rights Reserved.
NHRC-2 Repeater Controller
User Guide
Rev D PCB only
Contents
1. Installation
1. Electrical Connections
2. Adjusting the Audio Levels
3. Initializing the Controller
2. Programming
1. Controller Modes
2. Programming the Controller
1. Programming the Timers
2. Programming the CW Messages
3. Programming the Flag Bits
4. Recording the Voice Messages
3. Enabling/Disabling the Repeater
3. Operating
1. About the IDs
2. The Tail Message
3. Using the Tail Message as the Courtesy Tone
Index of Tables
• Configuration Flag Bits

NHRC-2 User Guide
NHRC-2 User Guide Page 2 2/28/2000
Copyright © 2000, NHRC LLC
All Rights Reserved.
• Electrical Connections
• Message Commands
• Morse Code Character Encoding
• Programming Memory Map
• Timer Address and Resolution
Board Layout
1. Installation
1. Electrical Connections
The controller uses a female DB9 connector (P1) for all signals. It requires
receiver audio and a signal present indication (CAS) from the receiver, supplies
transmit audio and PTT to the transmitter, and requires 13.8 volts DC for power.
Be very careful when wiring DC power to the controller, reverse polarity will
destroy the ICs. The connector pinout is shown in the table below.

NHRC-2 User Guide
NHRC-2 User Guide Page 3 2/28/2000
Copyright © 2000, NHRC LLC
All Rights Reserved.
Electrical Connections
Pin Use
1 Ground
2 +13.8 Volts
3 PTT (active low)
4 TX Audio
5 RX Audio
6CAS+
7CAS-
8 Ground/TX Audio Return
9 Ground/RX Audio Return
Receiver audio can typically be taken from the high side of the squelch control.
This audio must be de-emphasized with the controller's optional de-emphasis
circuit, which provides a -6dB/octave slope. Optionally, audio can be taken from
later in the receiver's audio chain, where it is already de-emphasized. Care must
be taken that this source of audio is not subject to adjustment by the radio's
volume control. If the receiver audio has not been properly de-emphasized, either
in the receiver itself or on the controller board, the repeater will have a very
"tinny", unnatural sound to it.
To de-emphasize the receiver audio on the controller board, install a 0.0068uF
capacitor in position C3, change R3 to 51K, and change R4 to 510K. These
values should be considered a good starting point. You may want to experiment
with the values of C3 and R4 to get better sounding audio. We have had
consistently good results with this de-emphasis network.
The receiver must provide a signal present indication (also called COR, RUS,
CAS) to the controller. Because of the varieties of polarity and state that this
signal can take, we have chosen to implement the controller's signal present input
with an opto-isolator (ISO1). The anode and cathode of the LED in the opto-
isolator are exposed through a current limiting resistor (R30). This allows easy
interfacing to active-high, active-low, and combinations of both to indicate the
presence of a received signal to the controller. Clever wiring can allow the user to
create CTCSS and COR, CTCSS or COR, etc. configurations. Note that both the

NHRC-2 User Guide
NHRC-2 User Guide Page 4 2/28/2000
Copyright © 2000, NHRC LLC
All Rights Reserved.
CAS+ and CAS- terminals must be connected to something in order for the
controller to detect the signal present indication.
Transmitter audio can be fed directly into the microphone input of the transmitter.
VR2 (marked TX LVL) is the master level control, used to set the audio level into
the transmitter. The transmitter's deviation limiter (sometimes called IDC) should
be set such that the transmitter cannot overdeviate, regardless of input signal
level. One way to adjust transmitter deviation is to set the transmitter deviation
limiter wide open (unlimited), adjust the controller's master output until the
transmitter is slightly overdeviating, then set the transmitter's deviation limiter to
limit just below 5 KHz deviation. Then reduce the controller's master output until
the transmitted audio does not sound compressed or clipped. Transmitter
deviation should be adjusted with a service monitor or deviation meter.
Transmitter keying is provided by a power MOSFET (Q6) configured in an open-
drain circuit. This can be used to key many transmitters directly. The MOSFET
essentially provides a closure to ground for PTT. For other transmitters, the
MOSFET can drive a small relay to key the radio. Although this MOSFET can
handle several amps, we recommend that no more than 250mA of current be
drawn through it, because the trace on the PC board is somewhat narrow.
2. Adjusting the Audio Levels
Preset all potentiometers to midrange. Connect an oscilloscope probe or DVM to
pin 15 of U3 (the M8870 DTMF decoder). (Use the power supply ground for the
'scope's ground or the DVM's return.) Key a radio on the input frequency, send
some touch-tones, and adjust VR1 (marked RX LVL) until DTMF decoding is
reliably indicated by a 5-volt level on U3 pin 15. Disconnect the oscilloscope or
DVM. Adjust VR2 (marked TX LVL) to adjust transmitter deviation, ideally
measured with a deviation meter or service monitor. Adjust VR6 (the beep level)
to set the courtesy tone and CW tone level.
The easiest way to adjust the ISD1420 input and output level is to select the
simplex repeater mode and record messages until the audio sounds right. VR3
(marked RECORD LVL) adjusts the record audio level into the ISD1420. Adjust
this control for the best sounding record audio. VR5 (marked SPEECH LVL) sets
the ISD1420 playback level. Adjust this control for best acceptable transmitter
deviation. VR4 (marked PROC RX LVL) is used to set the receiver audio level,
and may not need to be adjusted from midpoint.
3. Initializing the Controller
To initially program your secret code into the controller, you must apply power to
the controller with the pins on the INIT jumper, (SW1) shorted, putting the
controller into the initialize mode. Remove the jumper a few seconds after power
is applied. All of the values stored in the EEPROM will be reset to defaults, and

NHRC-2 User Guide
NHRC-2 User Guide Page 5 2/28/2000
Copyright © 2000, NHRC LLC
All Rights Reserved.
the controller will be ready to accept the 4-digit secret access code. This will
reset the CW ID to the default value "DE NHRC/2" as well. When the controller
is in the initialize mode the courtesy tone is 1/2 second long, instead of the usual
1/5 second. Key up and enter your 4-digit access code. The controller should
respond with the normal (1/5 second) courtesy beep. The secret access code is
stored in non-volatile memory in the PIC16F84 microcontroller. You will use
this code as the prefix for all commands you send to the controller.
2. Programming
1. Controller Modes
The controller can operate in 3 different modes:
• Repeater Controller Mode
The controller operates a full-duplex repeater, with a courtesy tone and
stored voice messages.
• Link Controller Mode
This is a variation of Repeater Controller Mode where the ISD1420 voice
storage chip can be deleted to lower the cost of the controller. This mode
is intended to control remote receivers that are essentially crossband
repeaters. Normally, when using link controller mode, the hang time is set
to 0 seconds, and the controller is programmed to suppress DTMF muting,
so the user's DTMF commands will appear on the input of a "downstream"
controller. The controller adds remote control, a timeout timer and CW ID
capability to remote or link receivers.
• Simplex Repeater Controller Mode
This mode allows simplex (as opposed to duplex) radios to be used as
repeaters. Up to 20 seconds of received audio is stored in the ISD1420
voice storage chip, and is "parroted" back when the user unkeys. The ID
message is played in CW.
2. Programming the Controller
All programming is done by entering 8-digit DTMF sequences. The first 4 digits
are the passcode chosen at initialization. The next 2 digits are an address or a
function code. The last 2 digits are the data for address or function. To enter
programming information, you must key your radio, enter the 8 digits, then
unkey. If the controller understands your sequence, it will respond with "OK" in
CW. If there is an error in your sequence, but the passcode is good, the controller
will respond with "NG". If the controller does not understand your command at
all, it will not respond with anything other than a courtesy beep, and then only if
the courtesy beep is enabled.

NHRC-2 User Guide
NHRC-2 User Guide Page 6 2/28/2000
Copyright © 2000, NHRC LLC
All Rights Reserved.
Responses to Commands
Response Meaning
"OK" Command Accepted
"NG" Command address or data is bad
courtesy beep
or nothing Command/password not accepted
If you enter an incorrect sequence, you can unkey before all 8 digits are entered,
and the sequence will be ignored. If you enter an incorrect address or incorrect
data, just re-program the location affected with the correct data.
In order to save space, reduce keystrokes, and eliminate some software
complexity, all programming addresses and data are entered as hexadecimal
numbers. Hexadecimal (or hex, for short) is a base-16 notation that is particularly
convenient for use in digital computer systems because each hex digit represents 4
bits of a value. The controller uses pairs of hex digits to represent 8-bit values for
the address and data of programming information. Any decimal number from 0 to
255mayberepresentedbytwohexdigits. Hexdigitsare0,1,2,3,4,5,6,7,8,
9, A, B, C, D, E, F, where A through F represent values from 10 to 15. To
convert a decimal number from 0 to 255 to hex, divide the decimal number by 16.
The quotient (number of whole 16s) forms the left (high) digit, and the remainder
forms the right (low) digit. Thus, 60 decimal = 3 x 16 + 12 = 3C hex.
The DTMF keys 0-9 and A-D map directly to their corresponding digits.
Use the *key for digit Eand the #key for digit F.
A 16-key DTMF generator is required to program the controller.
1. Programming the Timers
Timer Resolution. The timer values are stored as an 8-bit value, which
allows a range of 0 to 255. Some of the timers require high-resolution
timing of short durations, and others require lower resolution timing of
longer durations. Therefore, timers values are scaled by either 1/10, 1, or
10 seconds, depending on the application.

NHRC-2 User Guide
NHRC-2 User Guide Page 7 2/28/2000
Copyright © 2000, NHRC LLC
All Rights Reserved.
Timer Address and Resolution
Timer Address Resolution
Seconds Max. Value Seconds
Hang Timer 02 1/10 25.5
Timeout Timer 03 1 255
ID Timer 04 10 2550
Enter the 4 digit passcode, the timer address, and the timer value, scaled
appropriately. For example, to program the Hang Timer for 10 seconds,
enter pppp0264,wherepppp is your secret passcode, 02 is the hang timer
address, and 64 is the hexadecimal value for 100, which would be 10.0
seconds.
2. Programming the CW Messages
CW messages are programmed by storing encoded CW characters into
specific addresses in the controller. Use the Morse Code Character
Encoding table and the Programming Memory Map to determine the data
and address for the CW message characters. For example, to program
"DE N1KDO/R" for the CW ID, you would use the following commands:
CW ID Programming Example
DTMF
Command Address Data Description/Purpose
pppp0#09 0F 09 D
pppp1002 10 02 E
pppp1100 11 00 space
pppp1205 12 05 N
pppp133* 13 3E 1
pppp140D 14 0D K
pppp1509 15 09 D
pppp160# 16 0F O

NHRC-2 User Guide
NHRC-2 User Guide Page 8 2/28/2000
Copyright © 2000, NHRC LLC
All Rights Reserved.
pppp1729 17 29 /
pppp180A 18 0A R
pppp19## 19 FF End of message marker
The CW ID can store a message of up to 40 characters. Do not exceed 40
characters.
3. Programming the Flag Bits
Controller features can be enabled of disabled with the use of the
Configuration Flag Bits. These bits are encoded into a single byte, which
is programmed into the controller at address 01. Multiple flag bits can be
selected by summing their hex weights. For instance, to set up a link
controller with no ISD1420, no courtesy tone, and suppress the DTMF
muting, you would add 01, 10, and 20 to produce hex 31, which you
would then program into address 01 in the controller as pppp0131.
Configuration Flag Bits
Bit Hex
Weight Feature
001 ISDAbsent
1 02 Simplex repeater mode
204 n/a
308 n/a
4 10 suppress courtesy tone
5 20 suppress DTMF muting
6 40 use tail message for courtesy tone
780 n/a
4. Recording the Voice Messages
Stored voice messages can be played and recorded, and CW messages can
be played by using the message commands. Command 40 is used to play

NHRC-2 User Guide
NHRC-2 User Guide Page 9 2/28/2000
Copyright © 2000, NHRC LLC
All Rights Reserved.
stored voice or CW messages, and command 41 is used to record stored
voice messages.
To record stored voice messages, use command pppp410x,wherexis the
number of the message you want to record, found in the message contents
table. Unkey after the command sequence, then key up, speak your
message, and unkey. The controller will remove about 100 ms from the
end of your message to remove any squelch crash that might have been
recorded.
To play stored voice messages, use command pppp401x,wherexis the
number of the stored voice message you want to play. To play CW
messages, use command pppp401x,wherexis the number of the CW
messageyouwanttoplay.
You may wish to have a family member or member of the opposite sex
record your ID messages. The recorded audio sounds natural enough that
people have actually tried to call the amateur whose callsign is recorded in
the controller after the ID message plays!
3. Enabling/Disabling the Repeater
The repeater can be disabled or enabled by remote control by setting the value in
location00. Setthislocationtozerotodisable,ornon-zerotoenable. For
instance, to disable the repeater, send command pppp0000. To enable the
repeater, send command pppp0001.
3. Operating
1. About the IDs
When the repeater is first keyed the controller will play the "initial ID". If the
repeater is keyed again before the ID timer expires, the controller will play the
"normal ID" when the ID timer expires. If the repeater is not keyed again, and the
ID timer expires, the controller will reset and play the "initial ID" the next time
the repeater is keyed. If the repeater is keyed while the controller is playing a
stored voice message ID, the controller will cancel the stored voice message ID
and play the CW ID.
The idea behind this IDing logic is to prevent unnecessary IDing. For instance, if
a repeater user keys the machine and announces "This is N1KDO, monitoring",
the controller will play the initial ID, and no further IDing will occur unless the
repeater is keyed again. If users commence with a QSO, keying the repeater at
least once more, the controller will play the normal ID and reset the ID timer
when the ID timer expires. If the repeater becomes idle for one ID timer period
after the last ID, then the next time it is keyed it will play the initial ID. The

NHRC-2 User Guide
NHRC-2 User Guide Page 10 2/28/2000
Copyright © 2000, NHRC LLC
All Rights Reserved.
intent is that the repeater users only hear the initial ID the first time that they key
the repeater.
2. The Tail Message
The controller supports a "Tail Message" that plays the nth time the hang timer
expires. The number of times the hang timer must expire before the tail message
plays (n) is the "tail message counter" at address 5. The tail message counter can
be set from 1 to 255. The tail message is disabled if the tail message counter is
set to 0. Program the tail message counter value into address 05.
3. Using the Tail Message as the Courtesy Tone
The tail message can be used as the courtesy tone if bit 6 is set in the
configuration flags. In this case, you will likely want to set the tail message
counter value to 0 to keep the message from playing twice occasionally. The
message could store the sound of a bell, a dog's bark, or the repeater trustee
saying "what?"!
Tables
Message Commands
Command Description
400x 0 <= x <= 3, play CW message x
401x 0 <= x <= 3, play voice message x
410x 0 <= x <= 3, record voice message x
Message Contents
Message
Number Stored Voice CW
0 Initial ID ID message
1 Normal ID message timeout message ("TO")
2 Time-out Message confirm message ("OK")
3 Tail Message invalid message ("NG")