Novus NR3700-G-PPS User manual
USERS MANUAL
NR3700-G-
PPS
REVISION NUMBER
B
DATE
10/20/20
Page #:
1 of 20
www.novuspower.com
NR3700-G-PPS
NMEA-PPS Source
All information provided herein is the property of Novus Power Products LLC. The
information included may be reproduced without the permission of Novus Power
Products LLC. for the purpose of operating the Novus equipment.
USERS MANUAL
NR3700-G-
PPS
REVISION NUMBER
B
DATE
10/20/20
Page #:
2 of 20
www.novuspower.com
Contents
1.0 Overview................................................................................................................... 3
4.0 Input/Output Connectors/Mechanical.................................................................... 15
6.0 Alerts-Function..................................................................................................... 17
9.0 Technical Specification.......................................................................................... 18
10.0 Environmental and Mechanical ............................................................................ 18
Appendix: GNSS Command Reference........................................................................ 20
USERS MANUAL
NR3700-G-
PPS
REVISION NUMBER
B
DATE
10/20/20
Page #:
3 of 20
www.novuspower.com
1.0 Overview
GNSS Receiver
Self Test
PPS
3.3 or 5 V CMOS
NMEA Data
Alert
GPS Lock
Power Supply
AC Adapter
DC input to +-60vdc
The NR3700-G-PPS is a GNSS locked PPS/NMEA source. Ideal for critical
timing applications. The NMEA data is configurable as to the NMEA strings to be
provided. PPS cable compensation is also possible through the RS232 port. The
PPS can be supplied at either 3.3 or 5 Vdc CMOS.
The RS232 interface provides access to the NMEA-0183 data from the GPS at a
baud rate of 38.4K. The baud rate can be changed through the RS232 port.
The unit operates from power in the voltage range of -60 to +60 VDC in three
power supply ranges that must be specified at purchase. There is also an AC
power adapter available.
PPS pulse is a LVCMOS signal and is also short and transient protected. The
PPS has an accuracy of 30 ns rms and is available on the front panel as an
option with a SMA connector
The NR3700-G-PPS also incorporates built-in test to monitor critical parameters
such as the power supplies and other functions. The built-in test drives a front
panel indicator.
The GNSS lock status is provided by a front panel indicator. An unlocked state
can be detected via the RS232 port. Many systems will use this signal to detect
USERS MANUAL
NR3700-G-
PPS
REVISION NUMBER
B
DATE
10/20/20
Page #:
4 of 20
www.novuspower.com
a long-term GNSS loss of lock state which may be caused by an antenna or
cabling issue.
Less than 5 Watts of power from a 12 VDC nominal source is consumed. An AC
power adapter is available to allow direct operation from standard AC power.
Also, Novus offers related NR3700 products that can operate anywhere from –
60 to +60 VDC. Contact the factory for further details. There is a PCB assembly
version of this product (NR4400) which offers essentially the same functionality
and can be directly embedded in a system - smaller size and lower cost.
The output is transient and fault protected.
GNSS Receiver
Sensitivity
GPS
Tracking: -161 dBm
Hot Start: -161 dBm
Warm Start: -147 dBm
Cold Start: -147 dBm
Reacquisition: -161 dBm
GLONASS
Tracking: -157 dBm
Hot Start: -157 dBm
Warm Start: -143 dBm
Cold Start: -143 dBm
Reacquisition: -157 dBm
TTFF (Time to First Fix)
Hot Start: <5 sec (@-130 dBm)
Warm Start: 35 sec (@-130 dBm)
Cold Start: 40 sec (@-130 dBm)
・Active Anti-Jamming
・Advanced Multipath Mitigation
USERS MANUAL
NR3700-G-
PPS
REVISION NUMBER
B
DATE
10/20/20
Page #:
5 of 20
www.novuspower.com
The receiver needs at least four satellite vehicles (SVs) visible to obtain an
accurate 3-D position fix. When travelling in a valley, or built-up area, or under
heavy tree cover, you will experience difficulty acquiring and maintaining a
coherent satellite lock. Complete satellite lock may be lost, or only enough
satellites (3) tracked to be able to compute a 2-D position fix, or a poor 3D fix due
to insufficient satellite geometry (i.e. poor DOP). It may not be possible to update
a position fix inside a building or beneath a bridge. The receiver can operate in 2-
D mode if it goes down to seeing only three satellites by assuming its height
remains constant. But this assumption can lead to very large errors, especially
when a change in height does occur. A 2-D position fix is not considered a good
or accurate fix; it is simply “better than nothing”.
The receiver’s antenna must have a clear view of the sky to acquire satellite lock.
Remember, it is the location of the antenna that will be given as the position fix. If
the antenna is mounted on a vehicle, survey pole, or backpack, allowance for this
must be made when using the solution. The GNSS receiver provides power for
the LNA in the antenna. The unit was designed to provide 3.5 Vdc < 40 mA of
current.
To measure the range from the satellite to the receiver, two criteria are required:
signal transmission time and signal reception time. All GPS satellites have
several atomic clocks that keep precise time and are used to time-tag the
message (i.e. code the transmission time onto the signal) and to control the
transmission sequence of the coded signal. The receiver has an internal clock to
precisely identify the arrival time of the signal. Transit speed of the signal is a
known constant (the speed of light), therefore: time x speed of light = distance.
Once the receiver calculates the range to a satellite, it knows that it lies
somewhere on an imaginary sphere whose radius is equal to this range. If a
second satellite is then found, a second sphere can again be calculated from this
range information. The receiver will now know that it lies somewhere on the circle
of points produced where these two spheres intersect.
USERS MANUAL
NR3700-G-
PPS
REVISION NUMBER
B
DATE
10/20/20
Page #:
6 of 20
www.novuspower.com
When a third satellite is detected and a range determined, a third sphere
intersects the area formed by the other two. This intersection occurs at just two
points. A fourth satellite is then used to synchronize the receiver clock to the
satellite clocks.
In practice, just four satellite measurements are sufficient for the receiver to
determine a position, as one of the two points will be totally unreasonable
(possibly many kilometers out into space). This assumes the satellite and
receiver timing to be identical. In reality, when the receiver compares the
incoming signal with its own internal copy of the code and clock, the two will no
longer be synchronized. Timing error in the satellite clocks, the receiver, and
other anomalies mean that the measurement of the signal transit time is in error.
This, effectively, is a constant for all satellites since each measurement is made
simultaneously on parallel tracking channels. Because of this, the resulting
ranges calculated are known as “pseudo-ranges”.
To overcome these errors, the receiver then matches or “skews” its own code to
become synchronous with the satellite signal. This is repeated for all satellites in
turn, thus measuring the relative transit times of individual signals. By accurately
knowing all satellite positions and measuring the signal transit times, the user’s
position can be accurately determined.
USERS MANUAL
NR3700-G-
PPS
REVISION NUMBER
B
DATE
10/20/20
Page #:
7 of 20
www.novuspower.com
Antenna
Antenna - SMA
SMA female antenna connection. Provides internal 3.3VDC power at 20mA max.
The Novus NA103 Pole Mount Antenna or the Novus NA106 Magnetic Mount
Antenna are recommended for optimal performance.
The receiver and companion elements generate the PPS and NMEA serial link.
The serial link conforms to NMEA 0183 protocol. The 26 channel high-sensitivity,
high-accuracy Multi-GNSS receiver supports TRAIM, GPS, GLONASS, QZSS,
SBAS, Active Anti-Jamming and Advanced Multipath Mitigation Functions.
Typical Antenna Specs:
Frequency Band 1574 –1607 MHz
Antenna Gain 2 dBic @ 90°
Amplifier Gain @ 3.0Vdc: 26dB (typ)
Polarization RHCP
Out-of-band Rejection >60dBc @ f0 ± 50MHz
Impedance 50Ω
VSWR 2.0 Max
DC Input 2.8V - 6V
Noise Figure <2.0dB
Power Consumption 20mA (typ)
USERS MANUAL
NR3700-G-
PPS
REVISION NUMBER
B
DATE
10/20/20
Page #:
8 of 20
www.novuspower.com
PPS (Pulse Per Second)
The PPS (one Pulse Per Second) relationship with the NMEA data is shown
below:
The serial data timing is for the next rising edge of the PPS pulse.
There are a number of attributes for the PPS that can be controlled via the
RS232 port with the radio:
PPS Availability
There is a TCXO that is used to maintain the PPS in the event of GNSS loss.
The radio can be programmed to either have the PPS stop when GNSS lock
occurs or continue with the stability of the internal TCXO. The TCXO has a
stability shown below.
USERS MANUAL
NR3700-G-
PPS
REVISION NUMBER
B
DATE
10/20/20
Page #:
9 of 20
www.novuspower.com
For applications requiring a more stable PPS –a source such as an OCXO or
atomic reference should be considered. The PPS can also be enabled or
disabled based upon a calculated accuracy.
Cable Delays
The unit can be programmed to compensate for PPS errors due to cable length.
A compensation factor of +/-100000 ns can be used.
Pulse Width
The pulse width can be programmed from 1 to 500ms.
Factory Default Settings
PPS on when estimated accuracy is within 1 usec.
Pulse width is 200ms.
USERS MANUAL
NR3700-G-
PPS
REVISION NUMBER
B
DATE
10/20/20
Page #:
10 of 20
www.novuspower.com
Output Drive
The PPS pulse is a CMOS drive capable of providing 30 ma. The unit is available with
either 3.3 or 5 Vdc logic levels.
PPS Accuracy
15ns(1σ) (@-130 dBm)
50ns(1σ) (@-150 dBm)
The nominal accuracy of a PPS signal that is directly from the radio is on the
order of 25 ns rms. The signal will also have ~5 ns of jitter. The jitter is due to the
characteristics of the transmission channel - multi-path and other radio effects.
The long-term accuracy of the PPS is excellent. There are numerous reference
documents produced by NIST that define accuracy.
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