AMM-SD1 Series - Amplitude Modulation Monitors
Accurate, professional quality precision instruments for all types of AM transmitters and Broadcast Stations.
Radio Engineering Associates is pleased to offer our AMM-SD1 (Software Display)
series of AM Modulation Monitors. These devices represent a breakthrough in
accurate, easy to use and highly cost effective instrumentation for measuring
and monitoring Amplitude Modulation transmitters and signals.
Click to view full-size image
How it works The AMM-SD1 Modulation Monitor uses with a USB connected,
microprocessor based hardware interface and RF demodulator. This is connected
between the transmitter or transmission line and the display computer.
The hardware interface connects to the display computer using a USB interface,
and is shown below.
The Modulation Monitor Software is installed and run on the display computer,
and this software displays the percentage of modulation and modulation envelope
in a series of user-selectable windows. A screen shot of the Modulation
Monitor software is shown above.
Click to view larger image
A few Highlights of the AMM-SD1 Modulation Monitor
- Peak reading
The AMM-SD1 shows your actual modulation percentage at all times.
AM is an absolute value, peak based modulation system,
and the AMM-SD1 shows you the true peaks.
The monitor features a number of high resolution displays including
positive and negative Analog meters, positive and negative bar-graph meters,
and an oscilloscope-type display. The analog and bar-graph displays
feature peak-hold. The peak-hold shows you the most recent,
high positive and negative peak level.
- Instant Response
The software display of the AMM-SD1 responds instantly to your transmitter's
true peak modulation. This modulation monitor
is the perfect instrument for measuring and monitoring the modulation of complex, varying
audio signals such as voice or music.
- Meter Displays
The Analog meter display emulates a classic, direct illumination, large modulation
meter system which was popular starting in the 1940s, and continuing through the
The Bar-Graph meter features the unique R.E.A. positive-over-negative display
and lets you immediately and instantly determine the Asymmetry (positive
peaks as compared to negative peaks) of the modulated signal, in real time.
- Peak Flashers
Adjustable negative and positive peak flashers warn you when the modulation is getting too high.
- Extended Measurement Range
Unlike most other commercial modulation monitors, the AMM-SD1 will
accurately display positive peaks up to 160%, typical for many good-quality transmitters.
The AMM-SD1 is an exceptional value and has key features absent from other modulation monitors costing
many times more making the AMM-SD1 the highest value, lowest cost, peak reading monitor available!
If you use or operate any equipment using Amplitude Modulation (AM),
it is generally necessary (and in many cases, legally required) to
monitor your transmitted signal continuously while you
are on the air. Constant modulation monitoring will let you know the
transmitter is working correctly, and that you are providing sufficient
audio to the carrier without overmodulating. Furthermore, you will know
immediately that your audio is in the correct phase with respect to your
voice, microphone, processing and transmitting equipment. This is vitally
important if you want to have a loud, well modulated, distortion-free signal.
Proper monitoring and control of the modulation of your signal:
- Lets you know exactly what kind of signal you're putting out, and that everything is working properly.
- Ensures you will not transmit a distorted signal due to overmodulation ... and ...
- Helps prevent FCC trouble since overmodulation causes spurious emissions and is also a violation of FCC rules in most cases. Knowing when you are overmodulating and making corrective adjustments will keep you legal.
- Allows you to adjust your equipment to put more modulation in the positive (upward) direction, making the signal louder while avoiding distortion.
- Gives you a full-fidelity, off-air audio output. This output can be connected to a monitor system or headphone amplifier. You will know what you sound like and how adjustments change the sound.
- Shows carrier shift and other abnormalities that may indicate a problem with the transmitter or adjustment.
Simple to Install and Connect to a Wide Variety of Equipment
Connecting the AMM-SD1 to your transmitter is simple. The monitor includes
one RF pickup unit. The Pickup Unit is a high impedance device,
and consumes very little power (milliwatts in most cases).
Note: A standard RF pickup is included with the Modulation Monitor.
- Connecting to a Broadcast Transmitter Most AM Broadcast Transmitters include an RF output for connection to a modulation monitor. Simply connect the RF pickup unit to this output.
- Connecting directly, in line, with the transmitter output This type of connection is typical for non-broadcast equipment such as short wave, amateur, and other similar equipment. The RF pickup unit is connected directly to the transmission line with a T connector. (See picture). Various power level RF pickup units are available.
- Use with a LPAM / Part 15 (100mW) Transmitter The AMM-SD1 Part 15 / Receiver Interface is used to interface to low power transmitters, where a direct connection to the transmitter would be impractical. Click here for more information on the AMM-SD1 Part 15 / Receiver Interface.
- Connecting to a local AM receiver This type of connection is very useful when there are many miles between the modulation monitor and the transmitter. The AMM-SD1 Part 15 Transmitter / Receiver Interface is required.
- Other connection methods Contact us ! We can advise you of the best connection for your purpose.
Shown to the left is a typical amateur or CB installation. In this example, the rf pickup unit is connected to the antenna feedline using
a T connector.
You may also build your own RF pickup unit (plans and specifications are included)
allowing the AMM-SD1 to be used in a wide variety of environments, and with
virtually any AM transmitter of any power level. Radio Engineering Associates will
also build custom RF pickup units for you. Contact us with your requirements.
For Off-Air Monitoring, the AMM-SD1 features a
wide range, high impedance audio output. This output is suitable for
driving an audio monitoring amplifier, headphone amplifier or other similar
audio system. Note: This output cannot drive headphones directly.
The AMM-SD1 is used in many applications including:
- Standard AM Broadcast Stations
- Short-Wave Broadcast Facilities (particularly multi-transmitter facilities)
- Amateur Radio Stations using AM (not usable with SSB)
- Citizen's Band Radio (CB)
- LPAM (Low Power AM) Broadcasting (FCC Part 15) - Click Here for more info
- Carrier-Current (campus) Broadcasting
- Informational (travel information, traffic reporting, etc.) stations
- Radio Repair Shops and Facilities
- Educational Institutions
- Accurate, peak reading measurements of modulation.
- Separate positive and negative peak meters (100% Negative, 160% Positive) with peak-hold
- Instant display of modulation asymmetry.
- Adjustable threshold negative and positive peak flashers
- High fidelity audio output, suitable for driving external audio equipment.
- Remotely located RF pickup/detector units keep the RF at the transmitter or antenna feedline, where it belongs!
- Need to build your own RF pickup/detector unit? RF pickup/detector units are very easy to construct, allowing pickup units to be built into transmitters, if required
- 2.5% accuracy!
- Covers the entire MW and HF range from 500kHz to 30mHz
- Coverage can be extended to virtually any frequency or power level by using a custom detector. You may build your own detector, or we can supply a custom unit. Contact us with your needs.
- High Impedance RF input - uses a negligible amount of RF power, allowing the monitor to be used with low power transmitters without signal loss
- Built in the United States of America!
Computer Hardware and Software Requirements
Computer Hardware Requirements:
- Microsoft Windows XP (SP3 or better), Windows 7 (SP1 or better) or Windows 8
- High speed Internet connection only used for downloading the installation software (not required after the software has been downloaded, except for updates)
- Intel Pentium 4, 1.2gHz or better
- 500mb or more RAM recommended
- Good quality VGA or better video adapter
- 1 free USB "A" socket
Pricing and Availability: In Stock
Price: $199.95 (US Dollars)
- Model AMM-SD1 Monitor with a USB interface, and the Modulation Monitor Software License (software download from our software distribution server. CD Media is also available)
- 1 RF pickup unit with SO-239 connector. Note: Specify desired power level for the RF Pickup Unit when ordering. The following standard power level RF pickup units are available. Contact us if you need another power level:
- Direct Connect to a standard AM Broadcast Transmitter modulation monitor RF output (12V Max.).
- 200 - 1000 Watts (carrier)
- 50 - 500 Watts (carrier)
- 30 - 300 Watts (carrier)
- 10 - 100 Watts (carrier)
- 3 - 30 Watts (carrier)
- 1 - 10 Watts (carrier)
- LPAM - Part 15 Transmitter / Receiver Interface RF pickup unit - (For an additional $199.00)
- Other (contact us!)
- Interconnecting cable to connect RF pickup unit to monitor (1/8 inch shielded dual cable).
- User Manual
Options and Add-Ons
- Additional RF Pickup Units - $35.00
- Tee Adapter for connecting RF Pickups - $6.00 - 2 SO239 Female, one PL259 male
- Physical media containing the software. Note: Normally the software is downloaded from the R.E.A. software download page. This ensures you have the latest version of the software.
- LPAM - Part 15 Transmitter / Receiver Interface RF pickup unit - $199.00 when ordered together with the AMM-SD1, $234.00 when ordered as an additional RF pickup
Purchasing the AMM-SD1
How to Order:
- The AMM-SD1 Modulation Monitors are in stock! Click here to purchase.
- Contact us by Telephone: Our Number is 978-597-0010, 9:00AM to 5:00PM Eastern Standard Time
- By Email to firstname.lastname@example.org
- Paper mail: (see our mailing address, below).
If you are not completely satisfied with your purchase, you may return it within
15 days of receipt (in new condition in original packing) for a
full refund. Shipping costs are not refundable.
Radio Engineering Associates Inc.
79 Tyler Road
Townsend, MA 01469