diff --git a/firmware/hackrf_usb/usb_api_sweep.c b/firmware/hackrf_usb/usb_api_sweep.c
index 503e7f6a..c1a5f2b4 100644
--- a/firmware/hackrf_usb/usb_api_sweep.c
+++ b/firmware/hackrf_usb/usb_api_sweep.c
@@ -31,31 +31,55 @@
 #define MIN(x,y)       ((x)<(y)?(x):(y))
 #define MAX(x,y)       ((x)>(y)?(x):(y))
 #define FREQ_GRANULARITY 1000000
-#define MIN_FREQ 1
-#define MAX_FREQ 6000
-#define MAX_FREQ_COUNT 1000
+#define MAX_RANGES 10
 #define THROWAWAY_BUFFERS 2
 
 volatile bool start_sweep_mode = false;
 static uint64_t sweep_freq;
-bool odd = true;
-static uint16_t frequencies[MAX_FREQ_COUNT];
-static uint16_t frequency_count = 0;
+static bool odd = true;
+static uint16_t frequencies[MAX_RANGES * 2];
+static unsigned char data[9 + MAX_RANGES * 2 * sizeof(frequencies[0])];
+static uint16_t num_ranges = 0;
 static uint32_t dwell_blocks = 0;
+static uint32_t step_width = 0;
+static uint32_t offset = 0;
+static enum sweep_style style = LINEAR;
+static uint16_t range = 0;
 
 usb_request_status_t usb_vendor_request_init_sweep(
 		usb_endpoint_t* const endpoint, const usb_transfer_stage_t stage)
 {
-	uint32_t dwell_time;
+	uint32_t num_samples;
+	int i;
 	if (stage == USB_TRANSFER_STAGE_SETUP) {
-		dwell_time = (endpoint->setup.index << 16) | endpoint->setup.value;
-		dwell_blocks = dwell_time / 0x4000;
-		frequency_count = endpoint->setup.length / sizeof(uint16_t);
-		usb_transfer_schedule_block(endpoint->out, &frequencies,
-									endpoint->setup.length, NULL, NULL);
+		num_samples = (endpoint->setup.index << 16) | endpoint->setup.value;
+		dwell_blocks = num_samples / 0x4000;
+		if(1 > dwell_blocks) {
+			return USB_REQUEST_STATUS_STALL;
+		}
+		num_ranges = (endpoint->setup.length - 9) / (2 * sizeof(frequencies[0]));
+		if((1 > num_ranges) || (MAX_RANGES < num_ranges)) {
+			return USB_REQUEST_STATUS_STALL;
+		}
+		usb_transfer_schedule_block(endpoint->out, &data,
+				endpoint->setup.length, NULL, NULL);
 	} else if (stage == USB_TRANSFER_STAGE_DATA) {
-		sweep_freq = frequencies[0];
-		set_freq(sweep_freq*FREQ_GRANULARITY);
+		step_width = ((uint32_t)(data[3]) << 24) | ((uint32_t)(data[2]) << 16)
+				| ((uint32_t)(data[1]) << 8) | data[0];
+		if(1 > step_width) {
+			return USB_REQUEST_STATUS_STALL;
+		}
+		offset = ((uint32_t)(data[7]) << 24) | ((uint32_t)(data[6]) << 16)
+				| ((uint32_t)(data[5]) << 8) | data[4];
+		style = data[8];
+		if(INTERLEAVED < style) {
+			return USB_REQUEST_STATUS_STALL;
+		}
+		for(i=0; i<(num_ranges*2); i++) {
+			frequencies[i] = ((uint16_t)(data[10+i*2]) << 8) + data[9+i*2];
+		}
+		sweep_freq = frequencies[0] * FREQ_GRANULARITY;
+		set_freq(sweep_freq + offset);
 		start_sweep_mode = true;
 		usb_transfer_schedule_ack(endpoint->in);
 	}
@@ -65,7 +89,6 @@ usb_request_status_t usb_vendor_request_init_sweep(
 void sweep_mode(void) {
 	unsigned int blocks_queued = 0;
 	unsigned int phase = 0;
-	unsigned int ifreq = 0;
 
 	uint8_t *buffer;
 	bool transfer = false;
@@ -88,8 +111,16 @@ void sweep_mode(void) {
 		}
 
 		if (transfer) {
-			*(uint16_t*)buffer = 0x7F7F;
-			*(uint16_t*)(buffer+2) = sweep_freq;
+			*buffer = 0x7f;
+			*(buffer+1) = 0x7f;
+			*(buffer+2) = sweep_freq & 0xff;
+			*(buffer+3) = (sweep_freq >> 8) & 0xff;
+			*(buffer+4) = (sweep_freq >> 16) & 0xff;
+			*(buffer+5) = (sweep_freq >> 24) & 0xff;
+			*(buffer+6) = (sweep_freq >> 32) & 0xff;
+			*(buffer+7) = (sweep_freq >> 40) & 0xff;
+			*(buffer+8) = (sweep_freq >> 48) & 0xff;
+			*(buffer+9) = (sweep_freq >> 56) & 0xff;
 			if (blocks_queued > THROWAWAY_BUFFERS) {
 				usb_transfer_schedule_block(
 					&usb_endpoint_bulk_in,
@@ -102,10 +133,27 @@ void sweep_mode(void) {
 		}
 
 		if ((dwell_blocks + THROWAWAY_BUFFERS) <= blocks_queued) {
-			if(++ifreq >= frequency_count)
-				ifreq = 0;
-			sweep_freq = frequencies[ifreq];
-			set_freq(sweep_freq*FREQ_GRANULARITY);
+			if(INTERLEAVED == style) {
+				if(!odd && ((sweep_freq + step_width) >= ((uint64_t)frequencies[1+range*2] * FREQ_GRANULARITY))) {
+					range = (range + 1) % num_ranges;
+					sweep_freq = frequencies[range*2] * FREQ_GRANULARITY;
+				} else {
+					if(odd) {
+						sweep_freq += step_width/4;
+					} else {
+						sweep_freq += 3*step_width/4;
+					}
+				}
+				odd = !odd;
+			} else {
+				if((sweep_freq + step_width) >= ((uint64_t)frequencies[1+range*2] * FREQ_GRANULARITY)) {
+					range = (range + 1) % num_ranges;
+					sweep_freq = frequencies[range*2] * FREQ_GRANULARITY;
+				} else {
+					sweep_freq += step_width;
+				}
+			}
+			set_freq(sweep_freq + offset);
 			blocks_queued = 0;
 		}
 	}
diff --git a/firmware/hackrf_usb/usb_api_sweep.h b/firmware/hackrf_usb/usb_api_sweep.h
index 828647cd..427c1cb2 100644
--- a/firmware/hackrf_usb/usb_api_sweep.h
+++ b/firmware/hackrf_usb/usb_api_sweep.h
@@ -19,8 +19,8 @@
  * Boston, MA 02110-1301, USA.
  */
 
-#ifndef __USB_API_SCAN_H__
-#define __USB_API_SCAN_H__
+#ifndef __USB_API_SWEEP_H__
+#define __USB_API_SWEEP_H__
 
 #include <stdbool.h>
 #include <usb_type.h>
@@ -28,6 +28,11 @@
 
 extern volatile bool start_sweep_mode;
 
+enum sweep_style {
+	LINEAR = 0,
+	INTERLEAVED = 1,
+};
+
 usb_request_status_t usb_vendor_request_init_sweep(
 	usb_endpoint_t* const endpoint, const usb_transfer_stage_t stage);
 
diff --git a/host/hackrf-tools/src/hackrf_sweep.c b/host/hackrf-tools/src/hackrf_sweep.c
index 719a44a2..a5c0489c 100644
--- a/host/hackrf-tools/src/hackrf_sweep.c
+++ b/host/hackrf-tools/src/hackrf_sweep.c
@@ -37,10 +37,6 @@
 #include <inttypes.h>
 
 #define _FILE_OFFSET_BITS 64
-#define BLOCKS_PER_TRANSFER 16
-#define SAMPLES_PER_BLOCK 16384
-#define STEP_SIZE_IN_HZ 312500
-#define FFT_SIZE 64
 
 #ifndef bool
 typedef int bool;
@@ -99,9 +95,12 @@ int gettimeofday(struct timeval *tv, void* ignored) {
 #define DEFAULT_BASEBAND_FILTER_BANDWIDTH (15000000) /* 5MHz default */
 
 #define TUNE_STEP (DEFAULT_SAMPLE_RATE_HZ / FREQ_ONE_MHZ)
-#define MAX_FREQ_COUNT 1000
+#define OFFSET 7500000
 
 #define DEFAULT_SAMPLE_COUNT 0x4000
+#define BLOCKS_PER_TRANSFER 16
+#define FFT_BIN_WIDTH_HZ 312500
+#define FFT_SIZE 64
 
 #if defined _WIN32
 	#define sleep(a) Sleep( (a*1000) )
@@ -201,7 +200,8 @@ int rx_callback(hackrf_transfer* transfer) {
 	 * write output to pipe
 	 */
 	int8_t* buf;
-	uint16_t frequency; /* in MHz */
+	uint8_t* ubuf;
+	uint64_t frequency; /* in Hz */
 	float float_freq;
 	int i, j;
 
@@ -209,13 +209,16 @@ int rx_callback(hackrf_transfer* transfer) {
 		byte_count += transfer->valid_length;
 		buf = (int8_t*) transfer->buffer;
 		for(j=0; j<BLOCKS_PER_TRANSFER; j++) {
-			if(buf[0] == 0x7F && buf[1] == 0x7F) {
-				frequency = *(uint16_t*)&buf[2];
+			ubuf = (uint8_t*) buf;
+			if(ubuf[0] == 0x7F && ubuf[1] == 0x7F) {
+				frequency = ((uint64_t)(ubuf[9]) << 56) | ((uint64_t)(ubuf[8]) << 48) | ((uint64_t)(ubuf[7]) << 40)
+						| ((uint64_t)(ubuf[6]) << 32) | ((uint64_t)(ubuf[5]) << 24) | ((uint64_t)(ubuf[4]) << 16)
+						| ((uint64_t)(ubuf[3]) << 8) | ubuf[2];
 			} else {
 				buf += SAMPLES_PER_BLOCK;
 				break;
 			}
-			if(FREQ_MAX_MHZ < frequency) {
+			if((FREQ_MAX_MHZ * FREQ_ONE_MHZ) < frequency) {
 				buf += SAMPLES_PER_BLOCK;
 				break;
 			}
@@ -236,6 +239,7 @@ int rx_callback(hackrf_transfer* transfer) {
 			}
 			if(binary_output) {
 				float_freq = frequency;
+				float_freq /= FREQ_ONE_MHZ;
 				fwrite(&float_freq, sizeof(float), 1, stdout);
 				fwrite(pwr, sizeof(float), fftSize, stdout);
 			} else {
@@ -244,9 +248,9 @@ int rx_callback(hackrf_transfer* transfer) {
 				strftime(time_str, 50, "%Y-%m-%d, %H:%M:%S", fft_time);
 				printf("%s, %" PRIu64 ", %" PRIu64 ", %.2f, %u",
 						time_str,
-						(uint64_t)((FREQ_ONE_MHZ*frequency)-((DEFAULT_SAMPLE_RATE_HZ*3)/8)),
-						(uint64_t)((FREQ_ONE_MHZ*frequency)-(DEFAULT_SAMPLE_RATE_HZ/8)),
-						(float)STEP_SIZE_IN_HZ,
+						(uint64_t)(frequency),
+						(uint64_t)(frequency+DEFAULT_SAMPLE_RATE_HZ/4),
+						(float)FFT_BIN_WIDTH_HZ,
 						FFT_SIZE);
 				for(i=fftSize/8; (fftSize*3)/8 > i; i++) {
 					printf(", %.2f", pwr[i]);
@@ -254,9 +258,9 @@ int rx_callback(hackrf_transfer* transfer) {
 				printf("\n");
 				printf("%s, %" PRIu64 ", %" PRIu64 ", %.2f, %u",
 						time_str,
-						(uint64_t)((FREQ_ONE_MHZ*frequency)+(DEFAULT_SAMPLE_RATE_HZ/8)),
-						(uint64_t)((FREQ_ONE_MHZ*frequency)+((DEFAULT_SAMPLE_RATE_HZ*3)/8)),
-						(float)STEP_SIZE_IN_HZ,
+						(uint64_t)(frequency+(DEFAULT_SAMPLE_RATE_HZ/2)),
+						(uint64_t)(frequency+((DEFAULT_SAMPLE_RATE_HZ*3)/4)),
+						(float)FFT_BIN_WIDTH_HZ,
 						FFT_SIZE);
 				for(i=(fftSize*5)/8; (fftSize*7)/8 > i; i++) {
 					printf(", %.2f", pwr[i]);
@@ -303,15 +307,14 @@ void sigint_callback_handler(int signum)  {
 #endif
 
 int main(int argc, char** argv) {
-	int opt, i, result, ifreq = 0;
-	bool odd;
+	int opt, i, result = 0;
 	const char* path = "/dev/null";
 	const char* serial_number = NULL;
 	int exit_code = EXIT_SUCCESS;
 	struct timeval t_end;
 	float time_diff;
 	unsigned int lna_gain=16, vga_gain=20;
-	uint16_t frequencies[MAX_FREQ_COUNT];
+	uint16_t frequencies[MAX_SWEEP_RANGES*2];
 	uint32_t num_samples = DEFAULT_SAMPLE_COUNT;
 	int step_count;
 
@@ -409,10 +412,6 @@ int main(int argc, char** argv) {
 		return EXIT_FAILURE;
 	}
 
-	/* Plan a whole number of steps with bandwidth equal to the sample rate. */
-	step_count = 1 + (freq_max - freq_min - 1) / TUNE_STEP;
-	freq_max = freq_min + step_count * TUNE_STEP;
-
 	if (FREQ_MAX_MHZ <freq_max) {
 		fprintf(stderr, "argument error: freq_max may not be higher than %u.\n",
 				FREQ_MAX_MHZ);
@@ -420,18 +419,6 @@ int main(int argc, char** argv) {
 		return EXIT_FAILURE;
 	}
 
-	fprintf(stderr, "Sweeping from %u MHz to %u MHz\n", freq_min, freq_max);
-	frequencies[0] = freq_min;
-	odd = true;
-	for(ifreq = 1; ifreq < step_count*2; ifreq++) {
-		if (odd) {
-			frequencies[ifreq] = frequencies[ifreq-1] + TUNE_STEP / 4;
-		} else {
-			frequencies[ifreq] = frequencies[ifreq-1] + 3*(TUNE_STEP/4);
-		}
-		odd = !odd;
-	}
-
 	fftSize = FFT_SIZE;
 	fftwIn = (fftwf_complex*)fftwf_malloc(sizeof(fftwf_complex) * fftSize);
 	fftwOut = (fftwf_complex*)fftwf_malloc(sizeof(fftwf_complex) * fftSize);
@@ -508,7 +495,20 @@ int main(int argc, char** argv) {
 		return EXIT_FAILURE;
 	}
 
-	result = hackrf_init_sweep(device, frequencies, ifreq, num_samples);
+	/*
+	 * Plan a whole number of tuning steps of a certain bandwidth.
+	 * Increase freq_max if necessary to accomodate a whole number of steps,
+	 * minimum 1.
+	 */
+	step_count = 1 + (freq_max - freq_min - 1) / TUNE_STEP;
+	freq_max = freq_min + step_count * TUNE_STEP;
+
+	fprintf(stderr, "Sweeping from %u MHz to %u MHz\n", freq_min, freq_max);
+	frequencies[0] = freq_min;
+	frequencies[1] = freq_max;
+
+	result = hackrf_init_sweep(device, frequencies, 1, num_samples,
+			TUNE_STEP * FREQ_ONE_MHZ, OFFSET, INTERLEAVED);
 	if( result != HACKRF_SUCCESS ) {
 		fprintf(stderr, "hackrf_init_sweep() failed: %s (%d)\n",
 			   hackrf_error_name(result), result);
diff --git a/host/libhackrf/src/hackrf.c b/host/libhackrf/src/hackrf.c
index a6925611..676624e1 100644
--- a/host/libhackrf/src/hackrf.c
+++ b/host/libhackrf/src/hackrf.c
@@ -1810,23 +1810,70 @@ int ADDCALL hackrf_set_hw_sync_mode(hackrf_device* device, const uint8_t value)
 	}
 }
 
-/* Initialise sweep mode with alist of frequencies and dwell time in samples */
-int ADDCALL hackrf_init_sweep(hackrf_device* device, uint16_t* frequency_list, int length, uint32_t dwell_time)
-{
+/*
+ * Initialize sweep mode:
+ * frequency_list is a list of start/stop pairs of frequencies in MHz.
+ * num_ranges is the number of pairs in frequency_list (1 to 10)
+ * num_samples is the number of samples to capture after each tuning.
+ * step_width is the width in Hz of the tuning step.
+ * offset is a number of Hz added to every tuning frequency.
+ *     Use to select center frequency based on the expected usable bandwidth.
+ * sweep_mode
+ *     LINEAR means step_width is added to the current frequency at each step.
+ *     INTERLEAVED invokes a scheme in which each step is divided into two
+ *         interleaved sub-steps, allowing the host to select the best portions
+ *         of the FFT of each sub-step and discard the rest.
+ */
+int ADDCALL hackrf_init_sweep(hackrf_device* device,
+		const uint16_t* frequency_list, const int num_ranges,
+		const uint32_t num_samples, const uint32_t step_width,
+		const uint32_t offset, const enum sweep_style style) {
 	USB_API_REQUIRED(device, 0x0102)
 	int result, i;
-	int size = length * sizeof(frequency_list[0]);
+	unsigned char data[9 + MAX_SWEEP_RANGES * 2 * sizeof(frequency_list[0])];
+	int size = 9 + num_ranges * 2 * sizeof(frequency_list[0]);
 
-	for(i=0; i<length; i++)
-		frequency_list[i] = TO_LE(frequency_list[i]);
+	if((num_ranges < 1) || (num_ranges > MAX_SWEEP_RANGES)){
+		return HACKRF_ERROR_INVALID_PARAM;
+	}
+
+	if(num_samples % SAMPLES_PER_BLOCK) {
+		return HACKRF_ERROR_INVALID_PARAM;
+	}
+
+	if(SAMPLES_PER_BLOCK < num_samples) {
+		return HACKRF_ERROR_INVALID_PARAM;
+	}
+
+	if(1 > step_width) {
+		return HACKRF_ERROR_INVALID_PARAM;
+	}
+
+	if(INTERLEAVED < style) {
+		return HACKRF_ERROR_INVALID_PARAM;
+	}
+
+	data[0] = step_width & 0xff;
+	data[1] = (step_width >> 8) & 0xff;
+	data[2] = (step_width >> 16) & 0xff;
+	data[3] = (step_width >> 24) & 0xff;
+	data[4] = offset & 0xff;
+	data[5] = (offset >> 8) & 0xff;
+	data[6] = (offset >> 16) & 0xff;
+	data[7] = (offset >> 24) & 0xff;
+	data[8] = style;
+	for(i=0; i<(num_ranges*2); i++) {
+		data[9+i*2] = frequency_list[i] & 0xff;
+		data[10+i*2] = (frequency_list[i] >> 8) & 0xff;
+	}
 
 	result = libusb_control_transfer(
 		device->usb_device,
 		LIBUSB_ENDPOINT_OUT | LIBUSB_REQUEST_TYPE_VENDOR | LIBUSB_RECIPIENT_DEVICE,
 		HACKRF_VENDOR_REQUEST_INIT_SWEEP,
-		dwell_time & 0xffff,
-		(dwell_time >> 16) & 0xffff,
-		(unsigned char*)frequency_list,
+		num_samples & 0xffff,
+		(num_samples >> 16) & 0xffff,
+		data,
 		size,
 		0
 	);
diff --git a/host/libhackrf/src/hackrf.h b/host/libhackrf/src/hackrf.h
index 904207e0..a92f5051 100644
--- a/host/libhackrf/src/hackrf.h
+++ b/host/libhackrf/src/hackrf.h
@@ -47,6 +47,9 @@ ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSI
 
 #endif
 
+#define SAMPLES_PER_BLOCK 16384
+#define MAX_SWEEP_RANGES 10
+
 enum hackrf_error {
 	HACKRF_SUCCESS = 0,
 	HACKRF_TRUE = 1,
@@ -95,6 +98,11 @@ enum operacake_ports {
 	OPERACAKE_PB4 = 7,
 };
 
+enum sweep_style {
+	LINEAR = 0,
+	INTERLEAVED = 1,
+};
+
 typedef struct hackrf_device hackrf_device;
 
 typedef struct {
@@ -218,10 +226,11 @@ extern ADDAPI uint32_t ADDCALL hackrf_compute_baseband_filter_bw(const uint32_t
 /* set hardware sync mode  */
 extern ADDAPI int ADDCALL hackrf_set_hw_sync_mode(hackrf_device* device, const uint8_t value);
 
-/* Start scan mode */
+/* Start sweep mode */
 extern ADDAPI int ADDCALL hackrf_init_sweep(hackrf_device* device,
-											uint16_t* frequency_list,
-											int length, uint32_t dwell_time);
+		const uint16_t* frequency_list, const int num_ranges,
+		const uint32_t num_samples, const uint32_t step_width,
+		const uint32_t offset, const enum sweep_style style);
 
 /* Operacake functions */
 extern ADDAPI int ADDCALL hackrf_get_operacake_boards(hackrf_device* device, uint8_t* boards);