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NMEA Combiner / Multiplexers
Products and Features Overview
Model AIS
and Model AIS-C
The Brookhouse standard NMEA Combiner / Multiplexer combines NMEA 0183 data from up to four marine instruments ( NMEA-talkers ) into a single data-stream for input via a single computer port, or “ NMEA listener ”. A configurable fifth input port is available for receiving return data from a computer for auto pilot control or for connection of a NMEA HS talker such as an AIS receiver. The term " NMEA Multiplexer " is widely used, but the device is also often referred to as " NMEA Combiner ". Brookhouse multiplexers offer high reliability and unique features at affordable prices. Installation of a Brookhouse multiplexer is straight forward. All connections are made via clearly marked screw-terminals on the outside of the multiplexer.
The most important characteristic of a good multiplexer is its ability to maintain data-integrity even under very high NMEA input load conditions. This is to a high degree determined by the efficiency of the multiplexer's buffering mechanism. The buffering system of the Brookhouse multiplexers is second to none, which is reflected in the excellent performance. This is made possible by the use of the latest state of the art micro-processors and well-designed firmware. Read what Brookhouse users say about the product: Click here.
With AIS (Automatic Identification System) receivers now frequently used, the ability to combine standard low speed NMEA talkers and high-speed AIS in one data-stream has become an important requirement. The Brookhouse standard multiplexer models support connection of AIS receivers via a configurable (5th) input port. However, if besides AIS support, the multiplexer is also required to process return data from a computer or chart plotter, typically to feed an autopilot for steering to a waypoint or along a route, we recommend using one of the new Brookhouse multiplexer models with baudrate conversion (models AIS and AIS-C).
The following data-sheets describe 2
new AIS models with that are now available, both with baud rate conversion:
mux_ais.pdf
mux_ais_c.pdf
Brookhouse multiplexers offer many extra features, most of which are included in all models. During years of experience with setting up integrated computer/instrument systems, we have come across various problem areas in NMEA connectivity. To tackle these problems, we have created effective solutions embedded in the multiplexer firmware, which can be activated by the user, as needed.
We do not offer these extras in expensive "advanced" models, they are available in all Brookhouse multiplexers. The advanced features are activated and configured during a simple Setup procedure, whereby the options can be selected from a menu. Click here to see what it looks like. However, if only the basic multiplexer functions are required, no setup is necessary. Many of the Brookhouse multiplexer options are unique and are not available in other products. Some of them are described hereunder:
Filtering and NMEA data manipulation
Brookhouse multiplexers offer comprehensive filtering and data manipulation capabilities, even in the standard model. Filtering is very useful to alleviate the load placed on the navigation software or instruments by selectively removing redundant data. On the fly editing allows the user to program the multiplexer to make changes to NMEA sentences as they pass through the multiplexer. In integrated instrument/computer systems these tools, only found in Brookhouse multiplexers, are extremely useful for fine-tuning and will help to get the most out of instruments and computer. Not needed at the moment? You don't pay any extra for these features and it is good to know that if you encounter a NMEA compatibility problem one day, your multiplexer can offer a solution. Even complete NMEA sentence translations are possible. For example, you may install a new GPS that outputs NMEA 3.01 but your older autopilot needs NMEA 1.5 sentences. The multiplexer can be programmed in a simple way by the user to do the required sentence translation. You can also ask Brookhouse support if the required translation has been done before and if so, we'll be happy to give you the "script", which is loaded in your multiplexer following a few easy steps. Click here for more information.
Automatic GPS back-up switching
Another important feature, also unique for Brookhouse multiplexers, is GPS back-up switching. This solves the problem of switching to a backup GPS if the main GPS fails. This is particularly important when sailing in waters with many navigation hazards. Interruption in the electronic navigation is avoided which makes this a valuable safety feature. We received the customer comment recently that this mechanism alone justifies installing a Brookhouse multiplexer. (Click here for more information)
NMEA Data Pacing
Some instruments, such as some electronic compasses, send NMEA data at such high rates that it causes congestion. Navigation software slows down or cannot handle the large number of NMEA sentences. The Data Pacing option, which is available in all Brookhouse multiplexers, is the ideal solution to this problem. (Click here for more information)
NMEA bridge for Raymarine Seatalk
A low-cost Seatalk interface option is available for all Brookhouse multiplexers which allows connection of the Raymarine Seatalk bus to one of the multiplexer ports. Raymarine instrument data from all instruments, available on the ST-bus is translated by the multiplexer into standard NMEA sentences and output together with sentences from other NMEA sources. The mux "Seatalk port" is still configurable as NMEA port too. By combining the multiplexer function with the Seatalk to NMEA conversion, an efficient system is created which results in important cost savings. (Click here for more information)
Using a low-cost GPS PS2 mouse as primary or backup GPS
GPS mice can usually only be plugged in directly into a laptop or PDA. A low-cost PS2 connector option now allows a PS2 GPS mouse to be plugged into the Brookhouse multiplexer as one of the NMEA talkers. Power is supplied by the multiplexer. Read more here.
USB and wireless multiplexer connections
The USB option is very popular for connection to laptop computers without serial port and is sold with over 50% of our multiplexers. The USB port is extra, the USB model also has a serial port connector for output to a repeater, radar, etc. In the near future we will also offer a Bluetooth model for wireless connection to the computer.
There are 4 models Brookhouse NMEA Multiplexers available:
Our standard, very affordable NMEA Multiplexer, loaded with useful features. All connections and Baudrate select are external for easy installation. Optional RayMarine Seatalk to NMEA conversion (Seatalk bridge). Optional integral USB interface for use with laptops without serial port. Optional 5th port for AIS receiver. Click on the picture above for a detailed description, specs. and how to order.
Models NMUX-AIS and NMUX-AISC. The photo shows
model NMUX-AISC. Both models combine standard NMEA talker data at 4800bps
with high speed 38400 bps output from an AIS receiver. The combined data
stream is transmitted at 38400bps to a computer or chart plotter. With the
computer or chartplotter input set to 38400, the NMEA output is also
transmitted at 38400 bps. The reason is that in- and output baudrates of
computer ports and chart plotters such as the Raymarine C- and E-series
cannot be set independently and are always the same for both directions.
Consequently, if the computer or chartplotter's output is required to feed a
standard NMEA listener such as an auto pilot, a DSC radio, a repeater
instrument etc, the baudrate of 38400 has to be reduced to 4800. The
baudrate conversion function of the multiplexer is independent from its
combine-function, with its own input and output port. The only difference
between models AIS and AISC is that model AIS has an extra RS422 port for
output to the Raymarine C- or E-series. The USB and Seatalk options are
available for both models.
For full specs and detailded description, click on the following links for
data-sheets:
mux_ais.pdf
mux_ais_c.pdf
The Brookhouse model NMEA mux with user-programmable LCD display. It has all the features of the standard NMEA mux plus display unit with LCD and selection button. Seatalk support is optional. Optional integral USB interface for use with laptops without serial port. The compact display unit is an ideal NMEA and Seatalk repeater for use inside (e.g. at chart table). The LCD is now fully user-programmable. Any data embedded in NMEA sentences that pass through the multiplexer (including Seatalk) can be displayed in a format and at a screen position determined by the user, preceded or followed by user-chosen descriptive text or symbols. All for the price you pay elsewhere for a basic NMEA mux only. Click on the picture above for a full description, specs and how to order.
More technical information Brookhouse home
Note: Seatalk is a trade-mark of RayMarine.