Many start-up developers; Wi-Fi, alarm and other product installers; university labs and electronic hobbyists may not have the budget or desire for expensive equipment, yet they still need a good, basic, calibrated signal generator. Generally, low cost RF generators must be attached to a PC via USB to operate or be programmed, which hinders portability. Many are too heavy or cumbersome to take into the field.
However, the RF Pro Touch RF generator developed by Red Oak Canyon LLC is truly portable. Weighing only 12 ounces and small enough to fit in your hand, this compact RF signal generator can be used in an office, classroom, lab or in the field. The unit is fully self-contained and small enough to take to remote, hard-to-reach places. With its simple touchscreen interface, the RF Pro Touch is quick to set up and versatile enough to accomplish many filter and cable characterization and alignment tasks.
The RF Pro Touch contains an internal temperature-controlled reference with only 2.5 ppm variation from -30° to 85°C. The reference combined with the ADF4351 wideband and low phase noise synthesizer enables the RF Pro Touch to generate a low phase noise output from 35 MHz to 4.4 GHz. At 1 GHz, the phase noise is -91 dBc/Hzat 10 kHz offset; at 2.4 GHz, it’s -86 dBc/Hz. The phase-locked loop (PLL) setup of the ADF4351 has been optimized to give the best noise performance for both integer and fractional synthesis, with 1 kHz RF output resolution. The output power is adjustable from +10 to -55 dBm, enough range for most sensitivity measurements. For lower power, a fixed attenuator can be added to the output.
OPERATION
To operate the RF Pro Touch, a 50 Ω load is connected to the RF output SMA connector, and the frequency and output power are set with the touch of a few buttons before pressing RF ON on the screen. No complicated setup.
The RF Pro Touch simplifies frequency response and linearity-saturation characterization with easy-to-use frequency and power scan modes. The “Loop Forever” mode scans between a starting and ending frequency or power, with pre-defined steps and time delays between steps. Pressing start begins the programmed scan until it is stopped. For more timing control of the start of a scan pass, the “Once” mode starts at the initial frequency or power, runs to the ending frequency or power with the applied step increment and then stops, waiting to start again. In “Step” mode, scanning pauses at each frequency or power step. In any mode, the scan can increment or decrement in frequency or power.
Some measurements require two RF generators or that the RF generator synchronize with another source. Since no two reference sources are identical, two generators using separate frequency references will produce unwanted noise in the measurement. The RF Pro Touch provides both an external reference input and a buffered reference output, so the frequency reference of the RF Pro Touch can be used as the source or can be driven with another instrument. A button on the Settings screen switches between internal and external references. When using an external reference, the external reference frequency in the Settings screen should be set to ensure the correct RF output frequency.
The modulation input provides a convenient way to either frequency modulate or pulse the RF output (OOK modulation). When FM is selected, varying the peak-to-peak modulation input voltage, up to a maximum of 15 V, sets the desired frequency deviation. A 4 Vpp, 1 kHz sine wave develops a 250 kHz deviation at 915 MHz, while a 200 mVpp, 1 kHz sine wave develops a 30 kHz deviation at 2.4 GHz. A digital, 3 to 5 V signal controls the RF output in OOK mode, enabling high frequency switching that is useful for compliance testing.
In the office or lab, the RF Pro Touch can be powered with the 5 V power adapter. In the field, the RF Pro Touch operates for at least two hours on a single charge. To extend the life of the internal Li-ion battery, the screen can be set to auto-blank after it hasn’t been touched for a defined time. Normally, if the RF is on while using the constant or scanning modes, the display won’t blank, although this can be configured in the settings screen to extend battery life. If the screen has auto-blanked after timeout, and the RF is off, an auto shutdown timer can be set to turn off the unit to save the battery. The next time the unit is turned on, it will have the same configuration as when it turned off.
APPLICATIONS
As a practical, low cost tool, the RF Pro Touch is ideal for teaching seminars, antenna calibration, as well as pre-compliance testing to assess possible interference with radio and TV reception and radiated immunity testing. Signals generated by the RF Pro Touch and amplified by a separate power amplifier are transmitted using antennas aimed directly at a product to determine whether the product will be disrupted. Contractors who install coaxial and fiber-optic cable inside buildings, for distributed antenna systems (DAS) or small cells, can use the RF Pro Touch to verify RF signal integrity. Ham radio operators can use the RF Pro Touch to measure filter response and experiment with receiver and transmitter circuits.
Red Oak Canyon LLC
Spicewood, Texas
www.redoakcanyon.com