diff --git a/README.md b/README.md
index abf8daa..001861b 100644
--- a/README.md
+++ b/README.md
@@ -4,20 +4,27 @@ tcd is a hybrid digital voice transcoder for ham radio used by the new URF refle
 
 ## Introduction
 
-This will build a new kind of hybrid transcoder that uses AMBE DVSI-based hardware for vocoding digital voice streams used in DStar/DMR/YSF *and* David Rowe's open-source Codec2 used in M17. At a minimum, you need a USB-based DVSI device (or multiple devices) based on the DVSI-3003 vocoder. For proper interfacing, each 3003 chip (internally containing three AMBE vocoders) will be detected by your system and assigned a unique /dev/ttyUSBX device. As each ttyUSBX device is assigned to one of the two AMBE codecs, you need at least two 3003 devices.
+This will build a new kind of hybrid transcoder that uses AMBE DVSI-based hardware for vocoding digital voice streams used in DStar/DMR/YSF *and* David Rowe's open-source Codec2 used in M17. At a minimum, you need a USB-based DVSI device (or multiple devices) based on the DVSI-3003 or 3000 vocoder.
+
+This is the only transcoder that will work with the [URF reflector](https://github.com/n7tae/urfd).
 
 This software is loosely based on LX3JL's **ambed**, but is easily different enough to be considered an entirely original work. Here are some major differences:
 
 - tcd mixes both hardware-based and software-based vocoders, providing a bridge between the closed source vocoders used in DStar, DMR and YSF and open-source vocoders used in M17.
-- tcd uses the standard /dev/ttyUSBX for interfacing with the DVSI hardware. At lease two 3003-based devices are required.
 - **UNIX Sockets** are used to communicate between the reflector and this transcoder. This greatly simplifies the code and *significantly* improves transcoding performance.
-- tcd only supports DVSI-3003-based devices that use the ttyUSBX interface.
+- AMBE vocoders are dedicated to an assigned reflector channel. This prevents overloading when processing multiple voice streams and provides the best possible performance for the reflector's clients.
+
+## Constraints and Requirements
+
+Currently, only two AMBE devices are supported. You cannot use a 3003 and a 3000 device together. If you use a pair of 3000 devices, only 460800-baud deivces are supported. When using a pair of 3000 devices, you can only transcode a single channel. If you use a pair of 3003 devices, you can specify up to three transcoded channels. AMBE devices based on LX3JL's USB-3006 open source design (sold by Northwest Digital and others) contain a pair of 3003 devices and are ideally suited for *tcd*.
+
+Currently, this program must be run locally with its paired URF reflector. Remote transcoding is not yet possible.
 
 Only systemd-based operating systems are supported. Debian or Ubuntu is recommended. If you want to install this on a non-systemd based OS, you are on your own. Also, by default, tcd is built without gdb support.
 
 ## Download the repository
 
-In the same directory where you urfd repository is located:
+In the parent directory of you urfd repository:
 
 ```bash
 git clone https://github.com/n7tae/tcd.git
diff --git a/systemd/tcd.service b/systemd/tcd.service
index a20628c..a029840 100644
--- a/systemd/tcd.service
+++ b/systemd/tcd.service
@@ -5,6 +5,8 @@ After=systemd-user-session.service network.target
 
 [Service]
 Type=simple
+ExecStartPre=-/sbin/rmmod ftdi_sio
+ExecStartPre=-/sbin/rmmod usbserial
 ExecStart=/usr/local/bin/tcd
 Restart=always