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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 announce 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.

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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.

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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 1960s.

  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-HF1 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 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.
• 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. A suitable RF pickup is required.
• Other connection methods Contact us ! We can advise you of the best connection for your purpose.

Shown to the left is an rf pickup unit 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 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

Key Features:

• 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

• Microsoft Windows XP (SP3 or better) or Windows 7 (SP1 or better)
• High speed Internet connection 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:

Price Includes:

• Model AMM-SD1 Monitor with a USB interface, and the Modulation Monitor Software License (software download from our software distribution server)
• 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:
  • 200 - 1000 Watts (carrier)
  • 50 - 500 Watts (carrier)
  • 30 - 300 Watts (carrier)
  • 10 - 100 Watts (carrier)
  • 3 - 30 Watts (carrier)
  • 1 - 10 Watts (carrier)
  • Direct Connect to an AM Broadcast Transmitter modulation monitor RF output (12V Max.).
  • 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 - $30.00
• 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.

Ordering Information

• The AMM-SD1 Modulation Monitors are available! 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 orders@radioassociates.com
• Paper mail: (see our mailing address, below).

Satisfaction Guarantee!!

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.

Contact Us:

• General Information: info@radioassociates.com
• Technical Support and Questions: support@radioassociates.com
• Orders: orders@radioassociates.com
• Or just call: 978-597-0010