VOR-tester¶

Phase-shifting low budget¶

VOR - VHF omnidirectional range tester: VHF Omni Directional Radio Range (VOR) is a type of short-range radio navigation system for aircraft, enabling aircraft with a receiving unit to determine their position and stay on course by receiving radio signals transmitted by a network of fixed ground radio beacons. It uses frequencies in the very high frequency (VHF) band from 108 to 117.95 MHz. Developed in the United States beginning in 1937 and deployed by 1946, VOR is the standard air navigational system in the world, used by both commercial and general aviation. By 2000 there were about 3000 VOR stations around the world including 1033 in the US, reduced to 967 by 2013 with more stations being decommissioned with the widespread adoption of GPS. When the signal is received in the aircraft, two 30 Hz signals are detected and then compared to determine the phase angle between them. The phase angle by which the AM signal lags the FM subcarrier signal is equal to the direction from the station to the aircraft, in degrees from local magnetic north, and is called the “radial.”

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Oktober 22 2014 Bascom-AVR code Master / Slave / Trigger

We needed two sinuses of 30 Hertz, one free-running (Master) and another one phase-shifted (Slave). Three AVR’s, can be real small ones, two with an resistor-array to create a DAC. A Master, a Slave and a Trigger_slave. Each time the Master goes through the zero going up, it generates a INT, and another INT is generated on every element of the sinus. In this case build from 256 elements. The interrupts are handled by the trigger_slave. It compares a variable (something that can be changed by a potentiometer on the ADC. or in this case picked from a lookup-table) and every time this variable is the same as the element-counter from the Master, the slave is triggered. And you get a poor men’s phase shifter.

Master a steady 30 hertz signal

 'Master - Free-running 30 Hertz sinus generator

 $regfile = "m88def.dat"
 $crystal = 12000000

 $hwstack = 128
 $swstack = 128
 $framesize = 128

 Config Portd = Output
 Config Portb.1 = Output                                     'toggle by a start of the sinus
 Config Portb.2 = Output                                     'toggle at every element of sinus

'Config Portb.0 = Output

 Dim X As Byte
 Dim Y As Byte

 Do
 Restore Sinus
 For Y = 0 To 255

 Read X
 Portb.1 = 0
 Waitus 2
 Portb.1 = 1
 If Y = 0 Then
 Portb.2 = 0
 Waitus 2
 Portb.2 = 1
 End If
 Portd = X

 'waitus 124   =   30,5 Hz

 Waitus 123                                                  '30 herz with 123 us

 Next Y
 Loop
 End
 Sinus:
 Data &H80 , &H83 , &H86 , &H89 , &H8C , &H8F , &H92 , &H95 , &H98 , &H9C , &H9F , &HA2 , &HA5 , &HA8 , &HAB , &HAE
 Data &HB0 , &HB3 , &HB6 , &HB9 , &HBC , &HBF , &HC1 , &HC4 , &HC7 , &HC9 , &HCC , &HCE , &HD1 , &HD3 , &HD5 , &HD8
 Data &HDA , &HDC , &HDE , &HE0 , &HE2 , &HE4 , &HE6 , &HE8 , &HEA , &HEC , &HED , &HEF , &HF0 , &HF2 , &HF3 , &HF5
 Data &HF6 , &HF7 , &HF8 , &HF9 , &HFA , &HFB , &HFC , &HFC , &HFD , &HFE , &HFE , &HFF , &HFF , &HFF , &HFF , &HFF
 Data &HFF , &HFF , &HFF , &HFF , &HFF , &HFF , &HFE , &HFE , &HFD , &HFC , &HFC , &HFB , &HFA , &HF9 , &HF8 , &HF7
 Data &HF6 , &HF5 , &HF3 , &HF2 , &HF0 , &HEF , &HED , &HEC , &HEA , &HE8 , &HE6 , &HE4 , &HE2 , &HE0 , &HDE , &HDC
 Data &HDA , &HD8 , &HD5 , &HD3 , &HD1 , &HCE , &HCC , &HC9 , &HC7 , &HC4 , &HC1 , &HBF , &HBC , &HB9 , &HB6 , &HB3
 Data &HB0 , &HAE , &HAB , &HA8 , &HA5 , &HA2 , &H9F , &H9C , &H98 , &H95 , &H92 , &H8F , &H8C , &H89 , &H86 , &H83
 Data &H80 , &H7C , &H79 , &H76 , &H73 , &H70 , &H6D , &H6A , &H67 , &H63 , &H60 , &H5D , &H5A , &H57 , &H54 , &H51
 Data &H4F , &H4C , &H49 , &H46 , &H43 , &H40 , &H3E , &H3B , &H38 , &H36 , &H33 , &H31 , &H2E , &H2C , &H2A , &H27
 Data &H25 , &H23 , &H21 , &H1F , &H1D , &H1B , &H19 , &H17 , &H15 , &H13 , &H12 , &H10 , &H0F , &H0D , &H0C , &H0A
 Data &H09 , &H08 , &H07 , &H06 , &H05 , &H04 , &H03 , &H03 , &H02 , &H01 , &H01 , &H00 , &H00 , &H00 , &H00 , &H00
 Data &H00 , &H00 , &H00 , &H00 , &H00 , &H00 , &H01 , &H01 , &H02 , &H03 , &H03 , &H04 , &H05 , &H06 , &H07 , &H08
 Data &H09 , &H0A , &H0C , &H0D , &H0F , &H10 , &H12 , &H13 , &H15 , &H17 , &H19 , &H1B , &H1D , &H1F , &H21 , &H23
 Data &H25 , &H27 , &H2A , &H2C , &H2E , &H31 , &H33 , &H36 , &H38 , &H3B , &H3E , &H40 , &H43 , &H46 , &H49 , &H4C
 Data &H4F , &H51 , &H54 , &H57 , &H5A , &H5D , &H60 , &H63 , &H67 , &H6A , &H6D , &H70 , &H73 , &H76 , &H79 , &H7C
 Data &H0B

Slave triggered 30 hertz sinus

'Slave - triggered 30 Hertz generator

$regfile = "m88def.dat"
$crystal = 12000000

$hwstack = 64
$swstack = 64
$framesize = 64

Config Portd = Output
Config Portb.1 = Input                                      'trigger
Portb.1 = 1                                                 'pull-up

Dim X As Byte

Do
Restore Sinus

Bitwait Pinb.1 , Reset                                      'wait for trigger

Do
Read X
If X = &H0B Then
Exit Do
End If
Portd = X

'waitus 124   =   30,5 Hz

Waitus 126                                                  '29 hertz
Loop

Loop

End

Sinus:
Data &H80 , &H83 , &H86 , &H89 , &H8C , &H8F , &H92 , &H95 , &H98 , &H9C , &H9F , &HA2 , &HA5 , &HA8 , &HAB , &HAE
Data &HB0 , &HB3 , &HB6 , &HB9 , &HBC , &HBF , &HC1 , &HC4 , &HC7 , &HC9 , &HCC , &HCE , &HD1 , &HD3 , &HD5 , &HD8
Data &HDA , &HDC , &HDE , &HE0 , &HE2 , &HE4 , &HE6 , &HE8 , &HEA , &HEC , &HED , &HEF , &HF0 , &HF2 , &HF3 , &HF5
Data &HF6 , &HF7 , &HF8 , &HF9 , &HFA , &HFB , &HFC , &HFC , &HFD , &HFE , &HFE , &HFF , &HFF , &HFF , &HFF , &HFF
Data &HFF , &HFF , &HFF , &HFF , &HFF , &HFF , &HFE , &HFE , &HFD , &HFC , &HFC , &HFB , &HFA , &HF9 , &HF8 , &HF7
Data &HF6 , &HF5 , &HF3 , &HF2 , &HF0 , &HEF , &HED , &HEC , &HEA , &HE8 , &HE6 , &HE4 , &HE2 , &HE0 , &HDE , &HDC
Data &HDA , &HD8 , &HD5 , &HD3 , &HD1 , &HCE , &HCC , &HC9 , &HC7 , &HC4 , &HC1 , &HBF , &HBC , &HB9 , &HB6 , &HB3
Data &HB0 , &HAE , &HAB , &HA8 , &HA5 , &HA2 , &H9F , &H9C , &H98 , &H95 , &H92 , &H8F , &H8C , &H89 , &H86 , &H83
Data &H80 , &H7C , &H79 , &H76 , &H73 , &H70 , &H6D , &H6A , &H67 , &H63 , &H60 , &H5D , &H5A , &H57 , &H54 , &H51
Data &H4F , &H4C , &H49 , &H46 , &H43 , &H40 , &H3E , &H3B , &H38 , &H36 , &H33 , &H31 , &H2E , &H2C , &H2A , &H27
Data &H25 , &H23 , &H21 , &H1F , &H1D , &H1B , &H19 , &H17 , &H15 , &H13 , &H12 , &H10 , &H0F , &H0D , &H0C , &H0A
Data &H09 , &H08 , &H07 , &H06 , &H05 , &H04 , &H03 , &H03 , &H02 , &H01 , &H01 , &H00 , &H00 , &H00 , &H00 , &H00
Data &H00 , &H00 , &H00 , &H00 , &H00 , &H00 , &H01 , &H01 , &H02 , &H03 , &H03 , &H04 , &H05 , &H06 , &H07 , &H08
Data &H09 , &H0A , &H0C , &H0D , &H0F , &H10 , &H12 , &H13 , &H15 , &H17 , &H19 , &H1B , &H1D , &H1F , &H21 , &H23
Data &H25 , &H27 , &H2A , &H2C , &H2E , &H31 , &H33 , &H36 , &H38 , &H3B , &H3E , &H40 , &H43 , &H46 , &H49 , &H4C
Data &H4F , &H51 , &H54 , &H57 , &H5A , &H5D , &H60 , &H63 , &H67 , &H6A , &H6D , &H70 , &H73 , &H76 , &H79 , &H7C
Data &H0B

Trigger chip (made use of the master chip of this project)

$regfile = "m128def.dat"
$crystal = 16000000

$hwstack = 128
$swstack = 128
$framesize = 128

Dim X As Byte
Dim Y As Byte

Y = 128                                                     '180 degrees phase-shift

Trigger_slave Alias Porte.2
Config Trigger_slave = Output

Config Int7 = Falling                                       '0-crossing of Master
On Int7 Isr_routine

Config Int4 = Falling                                       'each element of Master sinus
On Int4 Isr_routine2

Enable Int4
Enable Int7
Enable Interrupts

Do
Loop
End


Isr_routine2:                                               'each element of Master sinus                      '
If X = Y Then
Reset Trigger_slave
Waitus 2
Set Trigger_slave
End If
Incr X
Return

Isr_routine:                                                '0-crossing of Master
X = 0
Return