QS1R Online Manual

For now please refer to the QS1R FAQ .

REV1 10.20.2011_1

1.0 QS1R Receiver Description

The QS1R is a software defined VLF through HF, 10 kHz though 62 MHz direct sampling receiver.

It uses a 16 bit, 125 MSPS analog to digital converter (ADC) to digitize the whole RF spectrum from 10 kHz to 62 MHz. The high speed 125 MSPS data stream is too fast to transfer directly to the PC, so a Cyclone III FPGA implements a Digital Down Converter (DDC) to reduce the sampling rate to something that the PC can handle. Data is transferred from the QS1R to the PC via a high speed USB 2.0 connection that can transfer up to 40 MBytes/sec to the PC.

The RF IN connector is a BNC. There is provision for supplying an external encode clock through a SMA connector. The QS1R requires a power source of 5-6 VDC at 1000 mA.

The QS1R has its own audio DAC output instead of using the computer's sound card for output. This results in very low audio latency important for CW use and use with transmitters.

1.1 QS1R Front And Rear Panel

external image qs1r_front_sm.jpg
PWR - Power LED
The power LED is illuminated when 5-6 VDC is supplied to the DC IN connector on the rear of the unit. The QS1R does not have a power switch and can be left on when not in use.

The clip LED illuminates when the RF input to the RF IN connector exceeds the clipping level of the Analog to Digital Converter (ADC). This occurs at approximately +10 dBm.

RF IN - Antenna Input
The BNC connector is the antenna connector for the QS1R Receiver.

CLK IN - External Clock Input
An external clock can be used to clock the QS1R. Please see the section on external clocking in this manual for further information. By default, the QS1R uses its own internal clock.

external image qs1r_rear_sm.jpg
DC IN - Power Input Connector
Connect a center positive 2.1 mm or 2.5 mm coaxial power plug supplying 5-6 VDC @ 1000 mA to this connector.

DAC OUT - Audio Output Connector
The DAC OUT is a 3.5 mm stereo jack for audio output from the QS1R. This output can drive an external amplified speaker, a set of headphones, or can be fed into the line input of your PC's sound card.

USB 2.0 - USB 2.0 High Speed Connector
Data is transferred to/from the QS1R through a USB 2.0 high speed connection to the PC.

I/O - IO/Expansion Connector
This Mini DIN connector is used for I/O expansion of the QS1R. It also carries the external I2C expansion bus.

2.0 FCC and CE Identification

2.1 IDENTIFICATION (FCC Part 2 Subpart J - §2.1074 and Part 15 - §15.19(b))

The QS1R Receiver is manufactured by:

Software Radio Laboratory LLC
8776 Shillington Dr.
Powell, OH 43065-9001

2.2 INFORMATION TO THE USER (FCC Part 15 - §15.21 and §15.105)

This equipment has been tested and found to comply with the limits for a Class B digital
device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable
protection against harmful interference in a residential installation. This equipment generates,
uses and can radiate radio frequency energy and, if not installed and used in accordance with
the instructions, may cause harmful interference to radio communications. However, there is
no guarantee that interference will not occur in a particular installation. If this equipment does
cause harmful interference to radio or television reception, which can be determined by turning
the equipment off and on, the user is encouraged to try to correct the interference by one or
more of the following measures:

  • Reorient or relocate the receiving antenna.
  • Increase the separation between the equipment and receiver.
  • Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
  • Consult the dealer or an experienced radio/TV technician for help.

Caution! Modifications to this device not expressly approved by Software Radio Laboratory LLC could void the user’s authority to operate the equipment.

The QS1R receiver is manufactured in Columbus, Ohio, USA.



Software Radio Laboratory LLC declares that the QS1R receiver complies with the European Community EMC standards:

ETSI EN 300 330-1
ETSI EN 300 489-1
ETSI EN 300 489-15

Compliance reports are available upon written request to Software Radio Laboratory LLC.

3.0 Software Installation and Misc Information

Power Supply
If you did not purchase the USA or Universal Power Supply and intend to use your own power supply with the QS1R please note: The QS1R Receiver requires 5-6 VDC @ 1000 mA. If you intend to run the QS1R with Skimmer Server, you should provide 5-6 VDC @ 2000 mA. The QS1R power jack can accept either a 2.1 or 2.5 mm CENTER POSITIVE power plug. NOTE: DO NOT EXCEED 6 VDC INPUT TO THE QS1R POWER CONNECTOR!

Software Installation

The latest SDRMAXII software installer can be downloaded from:

The latest SDRMAXIV Beta software installer can be downloaded from:


Installation instructions are at:


Much more information about the setup and operation of your QS1R is available on the QS1R Wiki:


Technical support emails:


The Wiki should be consulted often since it is continually updated with the latest information.